Rank/division being a measurement of your MMR would go a long way to solve all of these issues. Something feels severely off with getting 20-24 LP for a win and losing 10 when you lose just because your actual MMR dictates you fight Gold 2's with a Bronze 1 team. It's a super, super band-aid solution and it makes climbing -- specifically as a Support -- absolutely freakin' miserable.
Give equal amounts of LP for a win and a loss, and don't allow people to be matched up against someone a division or two ahead or behind them, _under any circumstance*_
It's going to go a long way to making sure the player experience is better than it currently is, because... ouch... there are so many complaints, a lot of them I think are valid, about the current matchmaking.
**_*Exceptions for smurfs._**