Why hasn't Riot made anymore Dunkmaster skins?

I feel like their is just so much potential for some amazing skins, with little interactions. We already have Dunking for Noxus. We could have representing Bilgewater she could carry around a Ball as her Idol and all of her tenticles could have little jerseys on. We could have dunkmaster representing Freljord And I'm sure there are others that Riot could come up with.

Heres a Gif for you guys to see some epic braum Dunks. http://giphy.com/gifs/SWjLsPrnmbwBy