The feedback that matters is financial. Unsub. End of story. Until that happens, decisions are made by a combination of producers, system architects, developers, etc. However, if the people above them see the numbers going down, you'll see something more drastic.

Since we have seen plenty of threads about people unhappy with the game but not SE doing much about it, it sounds like these unhappy people are either few and far between... or they are unhappy and keep paying their sub. If I had a customer that continued to pay me, I'd probably continue doing what I'm doing.