They do.
Orcs are so handy. I mean, as a concept. One of the more offensive aspects of D&D-style fantasy is how races all get assigned particular personalities and natures. It really just sort of supports the whole notion of ethnic profiling, only this is even worse -- whole species getting branded with a single character.
But virtually every fantasy RPG has "orcs" of some fashion or other, mainly in order to provide bad guys that nobody needs to feel bad about killing a lot. D&D of course has a dozen or so variations on the "orc" theme, all twisted and evil in different ways, but all needing killing. A lot. Hobogblins, gnolls, mongrelmen, whatever you call them, they're just human beings who have no right to live, and so delivering them to death is what good guys do.
Personally, I find it boring. Why would any sentient race NOT develop the breadth of personalities and philosophies that human beings do? Most of these races are described in such a pathetically narrow way that it's really impossible to imagine. Hobgoblins like order and discipline. Goblins are impish and savage. And so on. There cannot be thoughtful gnolls, orcs are never swayed by appeals to compassion or long-term interest. These races are thin, amateurish cartoons of human beings -- which can work in some games, to be sure (Kobolds Ate My Baby, for one (by the way, Kobolds Ate My Baby is, like, the greatest game EVER, if you don't know)).
I like what Joshua has done with his last few campaigns -- the "monstrous" humanoids are just other races and everyone more or less kinda sorta gets along. Works best without elves, of course, but then so much does. Let's not discuss elves.
Anyway, the monstrous races are almost always used as this cheap way to have thrills without cost. Like the demons in Buffy the Vampire Slayer -- technically, right, they're demons, so Buffster can just murder them right left and center and never feel a twinge of guilt, but... A lot of the demons that start turning up seem awfully... not so terrible. Just kind of plain folks, really, who have a line or three and then get Buffercized. And then there seem to be some demons that don't ever get killed, and just hang out with everyone else. I don't get it, but more to the point, I don't LIKE it (I guess that's coming clear), since it sucks all the actual human drama out of the situation. All the killing ceases to matter, ceases to be exciting on anything other than the most trivial of levels.
Which, again, is fine in a cartoon where kobolds are running around stealing babies. But for a game I'm going to invest the time to run a campaign in, insufficient.
Which is why DINO-PIRATES OF NINJA ISLAND doesn't have any races other than people. People are good. You have people, you have everything.
All that aside, Claudio did a pretty awesome job on this half-orc picture. That guy looks MEAN.