After reading this, I think EMPEROR_COW did a pretty good interview with Itagaki, there things I agree and there are things I disagree...
Part of his four main pillars would be something I give credit to since DOA is a game that has the correct balance when it comes to players to appeal niche, people who like fan service, casuals, fighting game players, & hardcore competitive players. It is not a bad idea to have an equal balance without overshadow others. But there are also certain comments that stood out the most from what you Itagaki-san said in your interview along with part of your trash talk about DOA5 after amount of reading. Which I have a lot to talk about to a point of a huge wall of text.
1. Identity: As far as DOAs identity as a fighter, I'm pretty sure the majority of people that aren't into DOA or what they view as a fighting game will never look at main DOA titles (not counting Xtreme spinoffs) as a fighter with or without Itagaki himself, maybe even have problems with Itagaki's creation from females, costumes, extra content (like the Breast Option, Age Limit, CG Gallery), being able to move the games camera, or the breast physics itself. Part of the ecchi, fanservice, or appearance would apply to themes of the games themselves or characters (plus there is still the age ratings, which there are certain content that you wouldn't see in CERO or other anime/manga, its also about how handle things when it comes to details). I think what matters more for DOA to identify as a fighter is gameplay by via screenshots & trailers, sex appeal shouldn't mean anything when it comes to identity and characters can have multiple appearance which they can be fighters as well (than just something you'd see out of other typical martial art groups that you would see in dojos, tv, action movies to name a few).
2. Sex Appeal & DOAX: Part of the DLC costumes at least the majority (there are exception) of them does reflect & is faithful to part of the DOA series when it came to the costume choices, but there are flaws to part of their DLC method. To Me what I think things gotten downhill was when Training Gear Set DLC came to play which every girl (that isn't any of the Japanese DOA Girls, Hitomi, & Marie Rose) were wearing Japanese Gym cloths which I think is just plain out of character since they weren't born or go to schools in Japan, nor they may not be into these uniforms if you know who they were (doesn't follow how older members use to did for costumes). Even NyoTengu who isn't from the human world was also wearing a Gym Uniform which also doesn't make sense along with other costumes that doesn't follow part of her background.
Even costume direction & themes are all over the places almost if it was being done by completely different members with no order in place nor focusing on one choice, even going as far as losing logic with the Bath Towels & Girls have nothing but leis covering their breast (as one of their pre orders) which doesn't make sense as an outfit that is meant for fighting (it should've been on seen cutscenes, gravures, & backgrounds). Which makes it look like certain members are either trying to immediate Itagaki's creation even they don't get what made them pretty solid or how to do it right. Another problem is that certain characters are getting ignored while others gotten way too much attention when it comes to DLC costumes, which is also pretty unfair to people who like these said characters.
While I understand to an extent of not wanting too much sexualism, but making DOAX as a firewall to appeal to the casual & people who love ecchi (like I do) in an attempt to separate the tone of a fighting series is not the way to handle it. People may only look at Dead or Alive as the Xtreme series, not the fighting game series because its part of DOA history since it uses their characters (despite DOAX isn't the main series). Which would require you to give up one or the other, like should DOA series remain a fighting game series or should it be just be the Xtreme series. Its like you need to know what your including in your game, or makes Me think that you forgot what you created in the past especially DOA1-4 along with the DOAX 1 & 2. You could've easily made your on IP (not include any DOA characters) if that's how you feel about DOAX.
3. Fleet & Dividing: This also part where your pillars will crack & completely fall flat on its face which all your efforts to appeal many players will go to waste. While I understand part of Ninja Gaiden since it was mostly an action game to begin with (there wasn't sexy content back in the 80s, until other games in the 90s including content that scene in other medias or what is going on in the world, even ones that will cause controversy) even modern NG1-3 took place before DOA, but making fleet between DOA & DOAX doesn't work that way like I've mentioned.
Trying to appeal to every gamer is no where a simple task to do or something you can't easily executed very well (unless you took a safer route that isn't a niche genre or doesn't have ecchi, trying to follow what other companies or developers are doing to a point of having a game exactly like other popular titles), it feels like something that isn't even worth trying without having members having their own mindset on what they're into or what taste do they have which is very conflicting which can easily be divided. Trying to getting them together into a universe will cause problems or people wouldn't want to play your game. Its like having pets to live together which they may not like each & will start fighting with each other, which dividing them would be the best method to prevent fights.
If you really don't want everyone divided your going to have to make a decisions on who do you want to appeal and it can't be both or everyone, which what you include in your game will be the path you will end up taking & can't turn back.
4. New Players/Beginners: Wanting to attract new players by all means isn't such a bad idea which can expand the gaming audience, but there is a problem. There is no easy way or any accomplishment to give newcomers to have a fighting chance. Even if these players were playing older DOA games or other fighting games, these newcomers will just mash buttons randomly when they're pretty new to fighting games including 3D fighters or wants to think "I think I can play this game" feeling like they're on top of the world until reality strikes them pretty hard when they discover tournaments, communities, & online which they might be pinned against a player with skills will end up with nothing but loses (maybe few wins or just 1 win). Almost every genre is about you succeed or you fail, fighting games is a type of genre about fighting skills which many newcomers will never get into fighting games may pick ones that are too easy which hardcore fgc will never touch those games because it doesn't have much to offer when it comes to high level play.
Fighting Games are like martial arts, which is something you can't automatically be a master within a day will end up with a humiliating defeat even certain hardcore fighters could be nasty to them along with hurting their feelings which those newcomers will be upset & just quit all together. There is no room for mercy when it comes to fighting one of the best players, which that would require them to study & practice part of DOA5U tutorials & command training from DOA1-5 is a better options to practice & improve your fighting skills.
Out of all the traditional fighting games which there is amount of high level play or technical skills required, I would even go as far to say that "DOA5 & VF5 are the fighters I would recommend to play for todays generation rather than something like Tekken 6 or TTT2 which has a lot of inputs & skills which is to the point of overwhelming not being able to learn everything." This video is better example on how fighting games are not easy:
Outside of what everyone thinks of Dead or Alive, I loved series for what it was from cute/pretty/sexy females, I also liked male characters, the gameplay itself, the extra options that effects the breast, the story itself, music, many choices of outfits & swimsuits (including DLC ones), scenes where girls are spending time at the beach, the tutorials it has to offer, photo mode, and the mini games from Xtreme spinoffs. I really don't want the series to be changed too much to the point where DOA became an empty shell, I just want them to improve & become one their best, and I also want the balance to be equal (at least with my own views). I do believe DOA5 isn't completely ruined or DOA itself isn't a mess either, the real mess could either be the new members or the company itself I'm even ending up looking at Itagaki as a mess (after the reading I had to do and hours I spend on making this post). After reading the post that was made in neogaf that Itagaki talks about, I feel like Itagaki was capable enough to just end the franchise, which the only one that can fell into tragedy & not continue on is the same man that created the series in the first place along with leaving stories unresolved where DOA will end in a cliffhanger that will never reach the conclusion, or choosing to not make a sequel. Which at that time, had control before he left Tecmo along with DOA.
I'm starting to think that the DOA series can do better without Itagaki since Devils Third hasn't been released yet and who knows what he wants to do for the series. The passionate DOA members can continue to keep the series alive. The only thing I can ever do for DOA, is just get a PS4 to get DOA5 Core Fighters, practice My skills to become a skilled player, & going to EVO to support the side tournament.