There really isn't enough diversity in the roster in terms of appearances. It's true there are too many anime looking or human characters in the roster and not enough cartoony looking characters like Banjo & Kazooie, K. Rool, Duck Hunt, ect. But it's a Japanese game so you can expect that.
I still kind of think even with us getting Ridley and K. Rool in this game we still don't have enough heavyweights in the game. I feel like there still should be a couple of more heavyweights in the roster like Porky, Dr. Eggman, ect.
There is even some major female characters not yet in the roster like Dixie Kong, Krystal, Chun-Li, Lara Croft, ect they should be in too. But alas, with Nintendo half of the time it's about recent characters and using them as promotion for upcoming games.