Since I have been reading this forum, I have yet to hear a legitamate reason why a player who wants to be able to blow up player cars has a problem doing so in a bad sport lobby. Everything is the same there except you get more people who play the same way. Someone please tell me what is wrong with that.
And I don't get all the 'people were chasing me, so I blew up their car' outrage. If people are chasing you, get out of your car near some cover and shoot them, or just keep driving, or drop a grenade/sticky, blow them up, and accept the fact that you will get a bad sport warning.
Voodu said it earlier - without bad sport, the game turns into jets and tanks and GTA 4. This game has evolved from that but if that is what you want to do, you can do so in a bad sport lobby. I'm not saying there is anything wrong with blowing up player cars, but bad sport provides a designated place to do that.