Mastery reset
I think mastery points should reset every season. It should be a symbol of what champions you main during that season. Otherwise, eventually its just going to be a useless number. Yes there will be one champion with higher mastery points than the others, but I don't want to see3 million mastery points on one champion. I just don't think its as interesting as my idea.
Instead I think every season the mastery points reset but the player gets an icon (on a champion masteries page) showcasing top 3 highest mastery point champions from the previous season. Then you can compare from season to season the amount you played certain champions.