I've visited this subject before, but it's worth repeating. In my experience, the most useless feature in any public bug-tracking system is the ability to vote on bugs.
As I mentioned in the linked article, users of bug databases aren't really representative of the user population at large, and the bugs that get large numbers of votes tend to be the "vocal niche-market" issues that stay unfixed for a long time because they're just not a priority for the people writing the software.
For commercial products, or Open Source products with corporate backing, the features that the paid developers work on will be dictated by the people doing the paying. While votes in the bug database might be some factor in their decisions, it's likely to be a very, very minor one. You're much better off making your requests through the sales channel: ask them what the best way is to get your bug fixed or feature in.
Volunteers for Open Source projects will work first on problems that effect them directly, and then on problems that don't necessarily effect them, but that their pride won't let them leave unfixed. Votes are unlikely to change this schedule. Calls from users to have a bug fixed that none of the developers think is important will be met with replies of "if you think it's that important, we'll be happy to accept a patch".
Keeping in mind that most people, when they encounter a bug, are probably more likely to either:
a) try to work around it
b) try some other software
then even know that a bug tracking system exists, much less register and open a bug in it...
Then yes, it could be said that people who use a bug tracking system are a "vocal niche-market".
Of course, voting can be helpful... look at PHP's bug voting system - it asks people to vote by reproducibility and severity ( http://bugs.php.net/bug.php?id=25172 )...
OSS developers who don't take advantage of that type of info about how widespread and sever bugs are will eventually end up coding only for themselves (see scenario b above).
While the vocal niche's can certainly skew results sometimes, I think there is a place for voting as long as the bug tracking system is (a) publicly acessible (b) clearly and visibly linked to from the UI of the said application and (c) sufficiently easy to use for the average user of the application/system itself. The point is that as long as you can involve the actual users then you can reduce the skew of the minority.
However, there are few bug systems integrated that well, so its still really pipe dreams ;-)