I don't see how me enjoying what I played but wishing there were more female characters available means it's not a fit for me.
There's plenty of characters SEGA could have put in - Rouge, Cream, Blaze - and that's just going by the Sonic franchise. Their other games (e.g. Mario & Sonic games) manage to have a greater female representation, so why can't Sonic & SEGA All-Stars? It had a number of supporting characters as playable (like, y'know, Big the Cat?) so it wouldn't kill them to add just a few more.