Considering the actual antagonist of MW2, i'd say America doesn't have the best light shone on it, in the grander scheme of things. Though you have to understand - products are always made with a target demographic in mind, the one that's going to make them the mucho dinero. For western developers, it's the western market. In particular, the USA and western Europe. Britain and America are where a lot of high profile releases see a lot of returns, so the protagonists are generally going to be someone relatable to that particular audience.
That said, i do think the demonisation of Russia has gone a bit too far. We're supposed to be over the Cold War already. (though i hear Putin isn't exactly clean himself) I can almost guarantee that the enemies of the future in new modern warefare games will be Asian and Middle Eastern. We're going to see more Medal-of-Honour-Esque games with terrorists as the enemies from roughly that region, but what i honestly think is that China is going to be the next "big bad". Since they're going to be the number one economic powerhouse in the world with considerable military force to back it up, the west is going to feel somewhat scared and intimidated. I'd bet a hundred quid that in the next couple of years we're going to see a Homefront style game where China invades America or Europe. Just wait. In fact, Homefront again proves my point of Asian antagonists - North Korean enemies. Think about that.
Most races have had some form of demonising and caricaturing though. As a Brit, we're generally represnted as having an excessively (if lovable) cockney accent or we're some sort of evil mastermind or race of evil people á la Killzone series. As Yahtzee said, a British guy could talk about rainbows and unicorns and still find a way to make it sound evil with our accent. And of course you have the typical evil German / Nazi stereotype, the street gang black people (GTA), the lazy Mexican (Red Dead). In fact, with any minority displayed, they tend to accentuate the difference to make them stand out. An awfully bad (and generally fake) accent, cultural signifiers (like "bling bling" on the black gangsters, a holy cross on a latino, smart suits / ties / fedoras for Italian mobsters etc). We've got a long way to go before we reach any kind of cultural harmony in games.
