Oh boy, have I had player input in future adventure design.
Player A - "You should make an adventure where I become seperated from the other players, and I have to fight a bunch of uber-baddies to save the rest of the PCs."
Player B - Have us rescue the NPC, then I will confess my love to his daughter. He will get mad, then the villain shows up we fight him, one of the PCs kills him, and then I find the item and...
Player C - I like big wars. I don't like small, dramatic fights. Everyone must think the same way as I do. I want to do an adventure of gurilla combat.
Only a few players do it, but those that do, do it all the time. All three are real examples, and only Player B would claim that I'm ruining their character when I didn't GM their script. A and C would come around, roll with it, then go back to giving suggestions.