No? Not as far as I can tell. I've played that game a lot and it's not broken. Also, it's really easy to get Akuma because it doesn't matter what the difficulty setting is, even very easy.
Not everyone plays Akuma, I for example play Sakura. As for numbers, not that many people play in the ranked matches it's not too surprising if you keep fighting the same few guys, championship mode has the majority of people playing it.