I dunno. In regards to the story/purpose of the roster, I find all fighting games to have totally shit stories and so story-relevant characters that are done well tend to be few, just like in DOA (exceptions being Hayabusa, Nightmare, Liu Kang, etc.)
As far as personality/complexity goes, again, all fighting game character rosters tend to suck ass at that, DOA no more than the others.
Now regarding character design and style, I actually feel like DOA does better than most. Now you could say "It doesn't have werewolves and shit" but I don't think you need those to still have a diverse selection of characters and playstyles.
So yeah. Hate me for it if you like, but I don't really have a problem with DOA's roster, save that 5U fucking needs Tengu back stat.