UserVoice would be great if it had a way to edit/suggest editions by other users. I've been using UserVoice (as user) for MS products for a long while, and the thing I notice the most is: there are repeated ideas, a lot of them, always. Sometimes because it's hard to find new ideas, sometimes because they are indeed different at some point.
For the second case, an edit / suggest edits feature could be of great value, so several users could aggregate multiple details into a single feature request. Also, the statistics of the 'most requested' features would be more realistic, as one feature will more likely be one feature with several votes, instead of several duplicate/similar features with just a few votes.