A meta-anthropic explanation for why people today think about the Doomsday Argument: observer moments in our time period have not solved the doomsday argument yet, so only observer moments in our time period are thinking about it seriously. Far-future observer moments have already solved it, so a random sample of observer moments that think about the doomsday argument and still are confused are guaranteed to be on this end of solving it.
(I don't put any stock in this. [Edit: this may be because I didn't put any stock in the Doomsday argument either.])
The moon and sun are almost exactly the same size as seen from Earth, because in worlds where this is not the case, observers pick a different interesting coincidence to hold up as non-anthropic in nature.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.