Junkyard Trundle Splash Art as well as Riot Girl Tristana

Why does Trundle's and Tristana's splash art still look like this? Shouldn't it have been updated along with the champion themselves? This is very outdated and I think should be worked on as it doesn't even come close to what the character actually looks like in game. Just a thought, any ideas when this might happen? I am a big fan of the splash art in general, and I understand there are a lot of them old, new and upcoming