Hard to create idea for Illaoi skin..?! Please..

I've been playing Illaoi lately as if she's my main. It got me thinking on why they haven't made a new skin for her yet. I can see how it can be somewhat "difficult" to conceive such an idea, but a little bit of effort from a creative mind is all it takes. Illaoi would be a perfect candidate for an Elderwood skin. Plant seeds from a pot to grow trees instead of tentacles. Tree vines can spring out to ensnare the life force of a champion. This idea came up while playing a game. I'm sure if I sat here for long enough today that I could come up with a great skin idea for every neglected champion in the game. The point is, I can't find an understanding on why there's quite a few champions that have needed skins for a long time, but never got the attention they deserve.