I think, at least the suggestions which are declined deserve an answer and a short explanation. If someone makes the effort to write a suggestion, then he deserves an answer, I think.
As a developer there are a lot of ideas the players will throw at you, 95% of them are bad or cant be implemented for one reason or another. Why should they give a reason for why they dont want to implement someones idea. They are busy enough as it is, and as i think has been mentioned before, in the few cases where someone might have a good idea often times there is no way to know if you can really implement it into the game until you try it, so there is no point in announcing your going to do it if you cannot know whether you can in fact implement it into the game, and you don't really know until your about done creating the feature if not done with it completely.
And a CM would really need to have a programming background and have a thorough understanding of the game and programming as it relates to the game so that they can filter out ideas that cannot be programmed into the game. The only people who fit this description are the developers, so the idea of having a CM as a mediator between the developers and community is completely pointless.