I think it depends a bit on how relevant community is to your application. If there's a community of users that is built up naturally by using your app (like there is at say Stack Overflow, which uses UserVoice) then you'll want to provide a place for the community to talk about features.

If your various users are generally unaware of each other, then I think that having a place for them to send you suggestions is fine.

My general thought is that building a system to handle suggestions before you have any is mildly premature. Provide an obvious way for users to send suggestions - a form or a prominent email address is usually fine - but wait until the flood of suggestions becomes a problem before solving it.