How about implementing some kind of voting system on official servers where players vote for certain settings to be changed. I think it is this kind of changes that could bring old players back and it is cheap to implement.
Let us not discuss the details like who would be eligible, how often, what settings, etc but rather discuss the idea itself, share your thoughts on this.
I think it sounds like an interesting idea to be honest as it kind of reminds me of the game Killing floor where in servers players get to vote on where they would like the next map to be or what game mode, difficulty, etc. will be as well.