Outdated splash art

I honestly don't understand how it is possible for some champions to still have the terribly outdated splash arts released years ago. I know some champions like (who had a splash update before) are up for a complete makeover but what about champions like etc. who are not close to getting a VU? Some of them are still using the crappy model paint over style while every damn poro and jungle monster has better artwork and visuals. We used to have a constant flow or splash art reworks. What is the point of stopping it when only a couple of really terrible ones remain?