Ranked
I don't know if I am just unlucky or its just the "norm" now to play Ranked like its normals because normals is "too easy" but I think Riot needs to implement a system to prevent this from happening. What I am talking about is trying out new champions and new lanes in ranked, yes auto filled happens, let your team know you are auto filled if you don't have a champion pool for that role.
I suggest a minimum mastery level or points for the champions you want to play in ranked to prevent this, of course this restriction being only applied if you get the roles you selected when queuing up, if you get auto filled then the restriction is lifted. Yes League of Legends is just a game for having fun but there are different modes for different kinds of players, if you are a "for fun" player why join the "tryhard" side and ruin the fun for everyone else?
Anyways that's one suggestion, throw your ideas in the comment section.