I play LOL quite a bit and a few things that I have noticed which cause a lot of the issues within the game between players:
1. Who lanes where. Most people respect calling lanes and who called first. Some don't and are unwilling to work it out. They either play what they want or announce that they are going to troll the game.
2. Right now there is no way to address that situation immediately (after the game is too late for your ELO or your time WASTED). The people who suffer are the rest of the team. That is immediate and long-term as you lose ELO if in a ranked game because someone didn't get their way. Also, you are the person being penalized for a jerk causing the issue: If you leave you get a scaled ban; When you lose, your ELO goes down AND you wasted your time.
1. Add a "Queue As" button instead of just play. This way people who want to play a certain lane or jungle can look for a game that has that slot open (you can even have it set up to allow a ranking of positions or "All Lanes"). Doing this will allow the people who only want to play a position (say Mid) to join a game where no one else only wants to play Mid. Problem solved.
2. Allow people to vote a person out of the team before the game starts and place the rest of the team back into queue. If a person is voted out often enough they should be treated like AFKers and/or any of the other negative feedback options - punishment that increases as they continue to ruin the experience of other people.
3. Add negative feedback to the choices at the end of the game like the teamwork/friendly/etc and if someone gets enough bad votes using the same scaling system in place for the positive feedback they should get automatic punishments (20 min ban, hour ban, etc). Having a separate way to vote positive versus negative is inefficient and confusing.
4. Add a section on the profile of each player that shows their positive and negative scores. A little public humiliation might start to get the attention of the people doing these things.
Overall, LOL is a great game IMHO, but increasingly the game is being ruined by players that seem to be trying to ruin it for others. Case in point, a recent draft (regular) match I was playing in started out on the wrong foot immediately. 4 positions were called and the guy in first position waited until that was done and then stated "I'm Mid" (which had been called already). When the person who called Mid said "um, I called Mid he responded by saying "I'm in first position and I don't care what you called. I'm playing Mid. BTW, what champ would you have played?". The person responded "Wow, really?". The rest of the team chimed in as well and told him that it was a "d@#$" move to do that. The original Mid decided to play the open lane and ended up telling the person he would have played Kennen. Immediately the new Mid player bans Kennen and says "now you can't play him". He ended up being horrible at Mid and fed the other team. If we had the option to vote him out we could have and also flagged him for his actions. Enough people do that and eventually he will either get the point, or it will catch up to him in scaling penalties.
I'm not saying that these options will solve everything, but at least they provide some relief from the TROLLS that have taken over a lot of the game. I personally would just be happy with the "Queue As" option, but the other options would be nice as well.