I got wrapped up in writing this comment and forgot about the larger context; my point is that it may be necessary (in the least convenient possible world) to choose a decision theory that does poorly on Newcomb's problem but better elsewhere, given that Newcomb's problem is unlikely to occur and similar-seeming but more common problems give better results with a different strategy.

So like the original post, I ask why Newcomb's problem seems to be (have been?) driving discussions of decision theory? Is it because this is the easiest place to make improvements, or because it's fun to think about?