A possible Alternative for end-season rewards
Somewhere on your profile it can show a total number of LP you have gained in the current season along with total LP Lost
So say you went from silver III to gold IV
on your profile it would say something like "Total LP gained this season: 675" "Total LP Lost this season: 247"
At the end of the season, your total number of LP gained could convert into RP to purchase a skin of your choice, players who climbed harder, get more LP => better rewards for harder work.
so 1500 Gained LP could convert into 1000 RP to purchase a 975 skin.
or something like that
This could also serve as a way to keep track of your ELO
What do you think?