I have no idea...mister vrex, you've brought up an interesting issue.
With that outta the way, one of the reasons I think for this is that people are insanely narrow-minded. I mean, even just playing as and thereby identifying with a black guy in GTA: San Andreas was about as well recieved as a flesh wound (yes, yes, i quoted yatzhee, big whoop, I DONT hinge on everything he says, but that fit well).
Me, for one, I'd like to see Final Fantasy VII remade with furries instead of humans. That'd be pretty interesting, don't you think? Or we could do it with a game people don't worship like it's the second coming of christ, Final Fantasy VIII.
Dunno why, the FF series just seem so good for it.
Alternatively, it would be interesting to see a game where you could play a game assuming the role of a shapeshifter and like, gained people's abilities by killing and absorbing th-wait a minute....
But still, Alex Mercer is human, and so are most of the people he "interacts" with.
It'd be a cool concept to put in Elder Scrolls V or VI i guess.
Or we could base a game in Oblivion style for example on D&D, what with the dragonborn, the elves etc.
Yes, the traditional hero races are mostly humanoid to some degree, but who knows, maybe you could play as a goblin?
Still, these are just my two cents and I don't claim to light the world on fire with this comment, but I hope I can make people see that a full-raccoon mario or a bear-barret could make for barrels of fun