Skins for *Mastered* Champions

I am not sure if this idea has been presented before. However, I think it would be pretty cool if, upon "mastering" a champion (reaching level 5) a player received a basic skin for that champion.

I understand that this may interfere with sales too much, so perhaps not a standard skin, but some kind of flashy appearance alteration for that champion that the player could choose to use in any given game. I am aware of the swag icon you can toggle, which is really cool; I love the feature and think maybe the idea can be expanded.

Maybe this is asking too much. I just thought it would be neat, and serve as a good incentive for players to stick with select champions they enjoy playing and master their mechanics. I have read in many places that this is one strategy to really improve your LoL play, along with your rank.

Does this seem like an interesting/possible addition?