As anything you implement has to be maintained for all future versions, as it creates expectations downstream, and as new features provide a reason to upgrade, it is important to start off an application with as few as features as possible that people will accept.
This then, is a quick list of the ways to stop new features being added too early
- Say "No".
- If that doesn't work, say "Later".
- When they come back, say "we changed our minds".
This may seem harsh, but it's for everyone's own good