It appears that all six games in the World Chess Championship have begun with 1.d4.  Why is 1.d4 so popular?  Is 1.e5 out of favor?  What about other opening moves?

You mean 1. e4? 1. e5 is impossible for white

There is nothing wrong with e4.. I guess they just don't feel like playing it? I dunno..

1.e4 has been much more extensively analysed than 1.d4. Ruy Lopez and Sicilian Defense have been analysed for more than 20 moves. You cannot surprise the opponent easily in openings so extensively analysed. But maybe the more important reason is, I think, 1.d4 is more favored by both Anand and Kramnik?

cause anand is was an e4 expert and just thinks he can now play anything krammik likes d4

Yeah, sorry about that.

That's what I was sort of thinking.  Just wanted to ask around.