Yes, the vast majority of Western fans certainly do like Japanese art, but for some reason a lot of the Western Harry Potter fans don't care for it. I can't explain it as I think the Japanese fan art is uniformly excellent. I suppose part of the disinterest is that the Japanese fan artists don't promote themselves in forums where Western HP fans hang out. For example, I only know of a couple Japanese HP fan artists on LJ, but I know there's a lot more on the internet.

And yes, taking and displaying artwork without permission of the artist is wrong no matter the reason, but I think that the fans who attempt to pass off other's artwork as their own are simply reprehensible.