I think they listen, but all depends on whose suggestions actually make it into the game. Do you take to heart the suggestions of the hardcore RPG crowd, or do you heed the advice of as one infamous poster terms them, the "shitbox kiddies"?

I think they do focus groups of both types, and glean as much as they can that way. However, what sounds good on paper doesnt always translate to good real-world results, due to just bad idea or unrealistic expectation altogether for either technical, budgetary, scheduling etc reasons. See Peter Molyneux