American here, and while there have been a lot of popular examples given in this thread, as far as I can tell, they are all conditional to other factors. The Fallout series' Enclave is a post-Armageddon United States, for example, rather than the United States we all know and love and unconditionally look up to as a moral paradigm all other nations jealously strive to match.
I would say that if the United States, in its more or less current form, was clearly displayed as the antagonists or a force of evil, many Americans would we curious about it and would love playing it if the game was fun and the message was critical or insightful; however, I doubt such a straightforwardly objectionable premise would grant it mainstream popularity.
Specter Von Baren said:
The inherent issue with creating a game, or rather just a story in general, with present America as the bad guys is that you have to get past one very important fact about America.
National identity.
(rest of snip)
It could be argued that the MacCarthyist era of popular anti-communist sentimentality led to some change in our willingness to be the good guys. Granted, most of our policy revolved around containment and obstinate support of non-communist governments/parties rather than direct military action, but the idea of pre-emptively striking the Soviet Union was not unpopular among common citizens.
It was an attitude of righteously confronting evil, but then again, that's the attitude that
every evil organization considers itself to have.