Possibly offensive question toward Riot

Just out of curiosity, I'm wondering why it takes so long to update splash arts? This isn't to be rude honestly, but the older splash arts (and quite a few of them frankly) need to be updated so as to fit with the current art style. Don't get me wrong, I'm in love with the most recent ones you did, they look wonderful. However, why does it take so long to update them? Before this most recent batch, I don't even remember the last time you updated splashes other than specific base splash arts for a few champions. Is the splash art team small?