I'm gonna be That Guy and say that I for one am thankful whenever the academy chooses some obscure dude I've never heard of from a random small country. I'm not gonna say that there isn't anti-americanism attached to the Nobel prize, but I think a bigger, more important part of it is that, y'know, literature is something that's done across the globe, and with much less of a focal point than, say, cinema (where, like it or not, such a gigantic percentage of the tradition and production belongs to America that you can't really not acknowledge it.) I mean, people assume it's tokenism or political correctness, but at the end of the day is anyone really gonna argue that a writer in Turkey or Vietnam or wherever is less capable of producing "outstanding work of an idealistic tendency" than a U.S. or english or french author?
Also, do universally acclaimed, best selling, rich dudes like Roth and McCarthy really need a Nobel? Neither one of them is particuarly lacking in the awards department, and both have their reputations solidified way beyond any honour that the award might bestow. What's the point of giving it to one of those two, besides stating something everyone already knows is true? Between that and honouring some dude with a lifetime's worth of awesome reading that barely anyone's heard about *, I'm way more interested in the second option.
* And I'm not saying all, or even most, recent Nobel laureates fulfill this criterion - but it's one thing to argue against specific choices and another to oppose them on principle.