I don't consider myself a player who is looking for something new. That would be strange, considering that we are playing Heroes 3. FM without expansions is very good because it fixes the game's inherent unfairness, unlike AIPs, which already change the gameplay. I'm not refusing to play with AIPs out of spite, but because I'm not looking for something new.
Regarding GM - make an exception, add the checkbox. It's pointless to try to convince conservatively minded people; it's a dead end. I wouldn't want to receive a pack of changes with GM that I don't really need. And I think other players will agree with me here.
Besides, who is against it (besides Davos)?