Why aren't there more pool party skins?

I've been looking at the splashes for the pool party skins, and realized that some of the champ designs you see in the background are actually really nice. I mean, the rough design process has already been done so why not put some of them in?

In PP. Renekton's splash, I really liked Zac and Gragas' looks. PP. Lee Sin's skin also had a really nice version of Orianna, which I really think should be implemented.

There were a few others I saw in Zigg's splash but I'm not entirely sure about those.

Anyway, you get my point. Thoughts?