Regular league gives you valuable rewards if you play enough, why not TFT??
When you play a game of summoners rift, you get XP, complete missions, and get honor points. All of these bonuses have a chance of giving you real value: blue essence as well as orange. Orange essence especially can buy skins or other RP costs.
In TFT, we get... icons?? The closest we get to "skins" is not LL themselves, but maps? There is no such things as honor or levels?
I hope in the future we can implement a system similar to SR, with levels, honor, missions, and chests that have the possibility of dropping LL skins.