You should gain RP when you move up a Ranked Tier
I'm talking like 200 RP when you graduate from (for example) bronze to silver and than another 200 going silver to gold. You can only do this once per account per rank, though to prevent abuse. Thoughts?
/edit: Ok, I read some of the replies and here's what i have to say: 200 RP would be the incentive to do better in ranked. If you went all the way from Bronze to Challenger, that would only net you 800 RP so it isn't a whole lot. I think it would reduce trolling in ranked because people would want that bonus 200 RP to rank up.