Now that you have recruited your vocal, engaged users, they’re going to start suggesting changes or telling you about new features they need. Hopefully they’ll provide patches and help test them. Quick, responsive iterations mean your contributors feel more satisfied and successful, and keep them coming back to help. Engaged contributors are more likely to get involved in more complex, riskier projects.
Also, don’t hesitate to throw away outdated features when you can do it without loss of effectiveness for the program or project. If your users aren’t using a feature, or you’re having to work hard to get them to use it, then maybe that feature isn’t important any more. – Raymond
Contributors respond when they’re engaged, and they’re engaged when they see that their contribution is valued. Accepting contributions — even small ones — from as many people as possible will mean that many more people will feel invested in the community, and are more likely to contribute again.
Put another way, volunteers are “paid” in gratitude and influence (ok, and also pizza). The more often you build in opportunities for quick iterations that respond to your contributor base, the more contributions you’re likely to gather.