@Riot, why can't we have more champion specific Summoner Icons?

We already have a few summoner icons featuring Teemo, Gragas, Veigar, Riven, Diana, Tryndamere and maybe some other champions but that's only the minority. I'd like some more diversity so I may get a chance to show the dedication to my main aswell.

I'm sure many other players would love an opportunity to represent their darlings in a proper way. Would it be too much to ask for a whole new set of unlockable/purchasable summoner icons for all those other champions?

(Here's an example: http://imgur.com/IKtXcWL)