Emotes, why do they have to go away?

I'm just wondering, I finally unlocked a Christmas icon last night and got one of the cool emotes that it does. However it makes me sad that I'll literally hardly ever get to use it since its so close to being over.

So can someone explain, why emotes are "removed" from the game? I mean if they are tied to the icons you equip, what's the point of removing the emote? What's the advantage in doing so? It seems like something that gives added value to obtained certain icons and in fact, could be another way to give both more to the player as well as a reason for players to buy more icons to obtain them(thus more money for riot), if they were a permanent thing that didn't get removed.

It seems like basically a negative thing for no real purpose behind it, to remove the emotes after the timed events are over, it takes value away from said icons and players when there's no real good reason to remove them.