Leveling up Skins @Riot

I have heard alot as your leveling up in the new system(and according to the video) when you get to a certain point you will get a skin for a champion you own...this sounds wonderful....

but

i have an idea... there are 138 champions....and say each champion has 3 skins..(no accurate i know) it doesn't take rocket science to figure out thats a butt tone of skins......and it would be more of a smack in the face to be say.... an main and get a skin for or ect ect....because we all know its not really that reliable to just give a skin for a champ you own.....

so just hear me out...why not keep the random skin thing....but let the player select the champion this random skin is for at-least...that why its not something for someone we don't like..or care about/....it would suck to be a mastery 7 on something then get up a really high player level..open up that fancy box..and get a skin for a champion you literally have no mastery on