Developers love feedback because that is the only real way they can know if what they do is any good. And it's not even only good feedback they love! As long as the criticism is based on fact, well argumented and constructive.
Developers can't read you minds and [b]they[/b] know their work, [b]they[/b] can use it. Once in a while I read comments about modules like "Nice start, but there is still a lot of work in it and it's a bit buggy." Well?? If you don't report bugs and if you don't make suggestions on how to improve a module, you can't expect that things will change to your taste.
You are not a programmer? Okay: There are new module releases in the module database now and then - download every module and test them!! That is the least you can do for the community.
Certainly developers won't answer every single PM or feature request you write - but be sure: They will see and appreciate your work.
This is what YOU can do for Postnuke ;-)