Hextech S rank Rewards

So I love the hextech system, and feel like the reward for getting that initial S rank is great. However, when you manage to get that S ranking on 4 or 5 champions in a few roles it starts to feel like you stop seeing much as far as rewards.

I think it might be a nice change if every time you get an S rank, you get either a key fragment, or a full key, after you have gotten the chest, or when your chest pool is empty.