I definitely think that devs should be in tune with the fan base before and after release. I think that many great ideas come from listening to fans. The problem is that for every good idea posted, or at the very least a realistic one, there are ten others that say something to the effect of "I want more boobies!" and "It should have voiceovers where everyone says my real name and I can develop a character with six arms and I can be a chaotic priest dwarf warrior mage and the story will still bend itself to my will…"

I can imagine sifting through forums posting fan ideas would get old very quickly.