One Piece and shipping
I've been thinking recently about the One Piece manga, and more specifically its lack of popularity in the US compared to Naruto and Bleach. Now, there are likely several reasons for this, including the wretched 4Kids hack job dub, but one that immediately comes to mind is this:

Oda doesn't ship. At ALL.

Now, you can argue that other SJ series also lack romance, but that's not really totally true. While they may lack couples, there are always tinges of romantic angst, usually one-sided. Bleach has Orihime's love of Ichigo, Eyeshield 21 has the occasional hints of Sena/Suzuna, etc. There's usually at least one character with feelings for another.

Not in One Piece. It is the adventure over all. Sanji may lust after Nami and Robin, but the chances of that being done as a serious plotline are zero. (Nami and Robin both being unusually strong characters for Shonen Jump females also helps.) But as much as I like Luffy/Nami myself, if it's done well, you can't really point to anything obvious in the canon and say 'look, Oda is trying to telegraph this to us!'. It isn't about the ships.

So, no canon wars = lower popularity? Not quite. :) There's another, bigger reason. Oda doesn't draw bishies. Oda's art is broad and comedic, and he is not known for his handsome guys. Even Zoro and Sanji, the two most frequently yaoi'd up guys, are more rugged than bishie. Not to mention also frequently used for comedic effect (Ooooh, hot hot Zoro snot bubble snores...)

Don't get me wrong, there's a lot of One Piece yaoi, and a lot of fangirls who love it. But the yaoi guys in One Piece are, well, more 'manly' than the ones in Bleach or Naruto. Could this be another reason for its lack of popularity?

Or maybe pirates just lose to ninjas.