Before hextech chests in league players would get 1-2 free skins a year for honor and rank.
You can get 52 hextech chests per year. Even if only a quarter are skin boxes, you'd still get like 4 skins just by rerolling the shards. And this is on top of the free skin you still get for ranked every year.
And that's not including events that randomly give out extra loot boxes. Which we didn't have in the past either.
Hextech loot boxes have been beneficial to players.