I actually care about it! Thing is, I need perspective, and the only way I can keep designing beautiful atmospheres is if I don't do it all the time. If I e.g. always put nature ambiance sounds in my games, it will become more a habit than something I really care about.
I don't have any actual facts about this, so it's going to be a wild guess, but compare Derek Yu's work on Aquaria and Spelunky - both are awesome games but with a very different focus. Perhaps it's because to be creative, change is needed once in a while.