just... the style. it just looks gross. D: and crazy. and insane. not my kind of thing.
/Puts on psychology hat.
One Piece is, for some, in the anime equivalent of The Uncanny Valley. To put it into a chart:
1. Anything by Osamu Tezuka
2. Moe or Fist of the North Star
3. Generic anime art style
4. Anything by Noaki Urosawa
5. One Piece
It's uncomfortable how close to any normal anime, but the way the author exaggerates everything feels strange to people. If anyone can call One Piece's art style anything, generic is not one of them. Crazy? Yes. Exaggerated? Yes. Very much like Saturday Morning Cartoons? Yes. But, the thing is, One Piece
is a Saturday Morning Cartoon. Not to mention the author
really likes American culture. Can't hate something for being what it should be. It's like saying 'I hate speakers because they make sound.' That's what it's supposed to be doing.
Also, One Piece is an absolutely staggering show. The pacing isn't perfect (in the anime, anyway), but the characters are awesome at best and solid but likable at worst. The villains have just as much of a fan-base as any main characters. The show can be funny, sad, awesome and rarely does it let up, except to catch its breath. There's never a concept that doesn't work and there's never a time where you aren't wondering about
something. There's plenty of room for exploration and the author is always rewarding his long time watchers with regular nostalgia bombs and makes use of having a long-ass series with an interesting, sprawling world and mythos. The guy knows exactly what he's doing. Something that happens in Chapter 1 that gets shrugged off as nothing gets explained in detail in Chapter 597. He isn't making it long for the sake of making it long and he wants money, he's making it long because he wants to tell an epic. And epics tend to be long. The money just kind of happened. One Piece is the manga equivalent of Dragon Quest. Kids, adults, old people, there's something for all of them. Something about the simple dream of a 17 year old boy to be King of the Pirates and going to fantastic places, meeting uncanny characters and having enthralling adventures attracts people.
That, and it's super-special-awesome.