Because it's more fun.
It's a bit misguided to make it a matter of taste anyway. There's nothing to discuss if you're making a decision on the basis of "fun". If you don't have rational reasons for making the judgment call, then you don't have anything of substance to actually share about the stack.
And I know Javascript way better than Clojure.
But building an app with Clojure feels like I'm writing high quality code.
Writing Node feels hacky and I get an uneasy feeling with it for some reason. I've never liked nodes callback-driven async approach to development.
This post summarizes my feelings towards Node better than I can: http://dosync.posterous.com/22397098