I can see why people don't appreciate the MAME categories now that I've looked into it a little bit.
It we take Beat'em Ups they show up in the "Fighter" Category.
Kungfu in Fighter / 2D
Final Fight in Fighter / 2.5D
and Art of Fighting in Fighter / Versus.
I think the console market came out with different terms for the genres than the arcade world and that's probably creating a lot of confusion.
For example I've always seen it this way
Final Fight -> Beat'em Up
Art of Fighting -> Fighter
Super Smash Bros -> Brawler
I'll have to keep thinking about the best way to do this.
Mame also does Role-Playing instead of RPG (your icons also don't respond to RPG I had to rename them

)