Is there a reason for this?
I believe that the main reason is that this is League of Legends, a game played from a top-down perspective, where if you'd give anything too much visual detail, it would likely end up looking very visually-noisy and blurred out.
This is the same case for incredible cloth details in splashes that aren't present in the textures in-game.
A good example for this thing done wrong is actually the health shrines in the Howling Abyss- While I don't really have good pictures of them, there's this zoomed-out cut screencap of a shrine and you can see from afar all these little designs that are actually more bothersome than good-looking (the shrines are actually super detailed, but detailed too well for their size, which makes it useless for the human eye because you have to zoom to the max in order to even catch all the little designs it's got, that is considering we're playing League from a top-down perspective).
https://i.gyazo.com/b1c0a2565930bd7d91a922a881e6ba59.png