Because japan tends to fuck-up stuff less.
Hell, I probably only like a handfull of Western Sci-fi; most of its so damn dull and uninspired. I stopped watching TV on a regular basis 2 years ago, most films these days suck, as well, and don't get me started on our music.
I'm not a big fan of many anime or manga, but it has a better track record in my book. So fucking what if every American reporter and his dog bends over backwards to tell the rest of the world about every single weird thing that happens in Japan, just so we can run around and practially cream our pants over how supposedly fucked up they are for having things we like to pretend we don't have? Sure, there are people over there who think parts of their own culture are 'geeky' or wierd, but shit, what's that compared here, where we can find people who hate all movies, novels, or non-inane conversation? Or people who think Pro Wrestling is real?