They'll listen to fans if they're reasonable, and the more they agree with them they more likely they are to consider their criticisms.
Anyway, it is kind of weird that the release schedule is slowing down despite the quick chapter releases in the magazine. I suspect "Bleach" could possibly get a similar treatment, though not as likely. It sells well enough for a quarterly release schedule, I just checked ICv2's Top 25 Manga Properties of 2008 and "One Piece" placed #9. It's weird that "One Piece", in terms of English scanlations, is right there with "Naruto" and "Bleach in terms of views/downloads/overall popularity, those three are the holy shonen trinity, but that's not the case with the official North American book releases, and I can see a few correlations. The anime hasn't been as successful on North American T.V. The main demographic that buys manga are teenage girls, and no offense to teenage girls reading this but I find compared to other shonen series that sell more "One Piece" doesn't have as much to appeal to teenage girls, particularly in the art-style. I think the pacing gets in the way as well. It doesn't kick into high-gear as quickly as say "Naruto", Bleach", "Death Note", or "Fullmetal Alchemist", and it makes things even harder when you're getting a quarterly release schedule, and now it's less than that. And on top of that less than half of what's been released in Japan has made to North America. More fans are into "One Piece" than when it was first published here years ago, but I can understand how frustrating it can be for fans waiting to collect these volumes when they're already so caught up on a story that already takes a while to hit its big plot points. Even the FUNImation dub, which has been taken off T.V. and has been brought back to the series beginning on DVD, is seemingly moving at a faster rate. VIZ isn't just a few volumes behind, they're over thirty volumes behind.