A tool like Uservoice or IdeaTorrent has a better signal to noise ratio for suggestions and feedback.
It's easier to find things, easier to tell which ideas are popular, and the most popular ideas don't scroll off the front page, so people are less likely to repost them.
That's a valid concern, but in the aggregate, with the number of players this game has, it would take a lot of sockpuppets to seriously skew the results, and even votes are just a guide, not a guarantee of implementation.
The most we could expect from OOO out of such a scheme is a threshold at which we're entitled to an official response of some sort, since you still need developer agreement that an idea is something the company wants to do.
Vote, alt, vote again, ???, false results.