Why is annie in wonderland a legendary skin

So i own annie in wonderland skin, not because i bought it when it first came out but because it was on sale during halloween and i bought it then, and i relaize, why does it cost so much? because honestly the only thing it changes is tibbers. prom queen annie is a 520 skin and that changes tibbers too. so why is annie in wonderland 1820? i didn't notice until i actually played in game that it doesn't have anything. legendary skins nowadays have different voice lines, all sorts of special effects, and the abilities are all different looking. annie in wonderland has none of that. So riot i ask you, why? i think if you can't change the skin to make it an actual proper legendary skin then we should at least have some form of other compensation be put to us. because honestly it might look nice but i'm a bit pissed that i have to pay 1820 for a skin that has nothing.