Why are there no rewards for mastery?

I'm not saying rito start handing out free legendary skins, but y'all can't even make free mastery themed chromas as a reward for rank 5 6 and 7…?! Red purple and blue chroma's for their base skins with bronze silver and gold highlights

It would certainly make the 512 champion mastery feel like it was worth something, especially since you have to pay for 6 and 7 with the currency you could spend on champions