when it comes to T7 Newbies I would have taken almost anyone over Shaheen, more specifically, Lidia, Kunimitsu II, Josie Rizal or even Lucky Chloe or just another female in general T8 has way too many dudes in the roster you have 9 females, a Leo, Kuma and Panda then like 20 dudes.
I guess to play "devil's advocate" for T8 (though this is more a critique for Tekken), with regards to the male:female ratio, I'd say compared to SF & MK, much of the female characters have no substance to them. I'ma separate this from a Story & Character perspective
Story
Even though Tekken has its joke aspects, seeing the last 2 games take a more serious tone and an aspect where every character plays some role in the story, unlike the Tekken of old (T1-5), where everyone has their own respective ending and you kinda just go off that, not a lot of the female characters fulfill that aspect. Part of it is because Tekken did a poor job of resolving conflicts that should have been ended (Bryan v. Yoshi, Asuka v. Lili) or they did a poor job introducing new rivals (Leo, Katarina, Eliza). Now we're in a position where it looks like we're gearing towards Kazuya vs Jin & because the Mishima's have been built up, no one else has been built with them outside a select few. Outside of Xiaoyu, Alisa, Nina, I guess Lili (maybe now she'll have a Karin from SFV-type role, unless Reina fulfills that), and it looks like Zafina, who else can you confidently say stands with Kazuya, Jin, Lars, etc. story-wise? I'll expand on Asuka in the second aspect, but could one really say Josie & Lucky Chloe can keep up with the grit of Tekken 8? And even the joke aspects, Josie & Kuma again? I'll say the only characters that could've kept up would have been Lidia, Anna, & maybe Kunimitsu II. Anna, to me should've been in the game but whatever. Likely DLC, which I don't like but gotta make money somehow. Lidia & Kuni could've been great additions, but this lies the problem I had with Tekken 7 (offline-wise): there's no expanded story. What made SF & MK successful in its latter aspects was with each new character there was more story. Sure the main story ended. But when you have a MK: Aftermath and expanded character episodes from SFV, people can latch on a character better. This did not happen with T7. Lidia & Kuni II to me felt more like, "Here are some new characters, go win tournaments with them for the Tekken World Tour until we nerf them and you drop them cause you can't win with them at the same level of consistency". If you don't give people an offline incentive to relate to a character, then all you have is "can I win with this character?" If yes: stay. If no: goodbye. Which then leads me to the second aspect:
Character:
This is where I'll expand on Asuka. This ties with story but here's the aspect of character where Asuka and much of the other female characters, outside a select few struggle. 1st: She has unresolved conflicts. We should have been done with her Lili & Feng arc. And we didn't even touch on the Kazama arc (which was supposed to happen with T6 but was retconned by Lars & Alisa). But since that was never done, she can only fulfill the Lili & Feng arc. But because of that hidden potential that was never realized, now we have Claudio. I just thought about the aspect of him being like an exorcist & such and how it ties to Asuka and her "potential". Asuka, to me, was supposed to fulfill that role. But again, Claudio didn't fulfill that role either (might happen in T8). So now, we have Jun who kinda fulfills both Asuka & Claudio's role (story-wise). Now this brings up the question: why does this matter with regards to character? Because you grow with the character. You relate with a character. You want to see a character encounter new challenges. New rivals. New opportunities of growth. Develop new personalities.And if you don't provide that, then all you can fulfill is: Is this character fun, can I win with them, and are they iconic? Fortunately Asuka does fulfill some of these aspects. But can you say the same for Josie, Lucky Chloe, Katarina, etc? Same with Julia. We should've been done with her Ganryu arc and in T6 it did seem like she was going a different direction. But then T7 made her into a joke character (likely DLC though). And these factors are why even Eddy, Bob, Fahkumram, etc. aren't in the game either, but Shaheen is. Now out of the new characters, I feel like Reina will likely be the only character with substance to make multiple appearances. And because Tekken did a poor job with a lot of these characters potential, now we're going back to Jun & such to hopefully fulfill that role again, while removing other characters because they're not impactful.
I could be wrong (and I hope T8 proves me wrong). But if anything I hope Tekken really looked at SF & MK (definitely MK more) for actual, offline character building. I think that would definitely help with that issue.