I posted this in another thread, but it seemed appropriate here too.
I main Ziggs. I do very well with him, and win most of the games I play Ziggs in. Following the advice many people have given, I try to stick with one or two champs, and at first it seemed to be working. But I played a game (as Ziggs mid) just today where I demolished my lane opponent, made some good ganks on both top and bottom lanes, and was 28/13/7 by the end of the game. And we still lost, because my team couldn't or wouldn't work together.
The frustration this brings on is enormous. I have no illusion that I'm the best player in the league, and I doubt I'll ever even make it to gold. But it really pisses me off when I do so well in a game and my team is either fighting so much that they can't focus, or they simply lack the teamwork and coordination it takes to win a game (worse yet is when someone decides to intentionally throw a game or leave because you didn't do something their way).
I don't doubt that there are a lot of players with great potential in bronze who simply can't make it out because they consistently get matched with trolls, feeders, and toxic players. And if you get matched with a known troll or rager, you LOSE LP for dodging! It's a lose-lose situation: either you dodge and lose LP to avoid losing from a troll, or you play through the game and lose a minimum of 20 minutes of your life and LP because there's a troll.
The only time I ever intentionally dodge a game is if I'm matched with someone who I know (from previous experience, not just on my own initial impression of someone) is going to either throw, troll, or rage so hard that the game would either be a loss or absolutely zero fun.
And I've said it before, but I truly think that adding someone to your ignore list should remove them from your pool of possible teammates. It's bad enough if you hit 'play again' after a match and get stuck with the same troll who just ruined your game, but nothing is worse than ignoring a rager or troll in one game and taking a break for an hour or two, only to come back and be matched with the exact same person again.