Seasonal/Holiday Summoner's Rift

Winter Summoner's Rift is in alpha right now, but why just winter? Why not have Summoner's Rift change season's to keep the game fresh? I'm fairly sure all it is is texture changes on the map, maybe a few changes here and there that aren't just texture's but over all the walls don't change in terms of size or shape just aesthetics so how come we don't have a Seasonal Summoner's rift or different texture's on Summoner's rift in general?

I personally think it would be pretty cool if we had a Spring, Autumn and Winter rift (the summer rift would probably be the current rift map) and maybe even have some changes with holiday's, or just re texture's of the rift? (I do understand its a little difficult to do but it's still cool to think about.)

And i really can't think of any legitimate problems with having alternative texture's for the rift aside from the usual problems we get from patch to patch with the map anyway.