Totally agree with the views expressed here.
I’m constantly a victim, yes I said victim, of this sort of player.
The game I’d run would be set in a pretty dystopian setting, yet for what ever reason their characters behave as if they were in modern day America.
Three role playing campaigns came to a grinding halt because of this (a standard D&D game, an Iron Kingdoms game, and a custom setting I wrote).
Because of that I sat down and just wrote what I call “Hard-Coded Rules”. Basically a set of game rules that affect the classes and races and at the same time bind the setting to them. This prevents some of what OldHat is mentioning. The way I figure; if the player’s character can’t do something do to game mechanics or hefty penalties, the player won’t attempt it.
I stopped calling races, races, and began calling them Species. I also defined exactly who could mate with whom and who hated who. You might think of that as silly, but it sets forth ground rules and answers a lot of questions (such as what’s a half-elf).
Here are some excerpts from my Axion campaign setting:

And this is the section under Faction

Basically the races (species) are bound to the classes which are bound to the factions. So from day 1 a player is sort of “locked” into a specific cultural disposition. This method requires a lot more work from the game designer or writer. In the case of a video game, a developer would have to have full content for the specially defined culture.
Now you might think that this might limit a player’s roleplaying options and pigeonhole a character into a pre-defined stereotype. On the contrary, from what I’ve seen so far it actually promotes some interesting backgrounds, roleplay, and creates situations where the characters may be at odds. This opens up plotlines, side quests, and all sorts of exciting moments that would otherwise be absent.
Other IPs should do the same. Particularly those that have hard set cultural dispositions. Iron Kingdoms is a perfect example of an IP that could use some of the mechanics described above. When I ran Iron Kingdoms we had players wanting to be from all over the place. The campaign setting never states what attitudes anyone has towards each other. So in the end it was one big happy family, even though it contained people from the Scharde Isles (Cryxx), Caspia (Cygnar), and Khador. Perhaps that’s what the designer wanted. It certainly did not feel like we were playing in the WarMachine mythos, but more like a normal D&D campaign with lackluster gun rules and the occasional Golem Steam Jack for show.
One reason why I can’t stand playing Warhammer Online is that the Orcs are teamed up with Chaos and Dark Elves (and High Elves with Dwarves respectively). Something bugs me seeing a couple Witch Elves chatting it up in the middle of an Orc camp.
I blame the designer/developer for that sort of thing. If they clearly defined who hates who, who fights who, and who likes who, you wouldn’t have half those issues come up. If the designer/developer stays consistant and doesn’t veer off that, those issues shouldn’t creep up.