You know, I have to say that the threads that get heated generally are in the Politics or Heated Debate threads. There is a place for that, and I think its a good thing for former JW's to stretch their muscles.
Speaking for myself, I learn as much as I give on some of those debates. To work through the issues and learning to be a responsible informed citizen is an important step for people who leave JW's.
It's also a good reminder to me that the world is a rough place. One selling point JW's use quite a bit is their utopian view of their "spiritual paradise", and how arguments and heated emotions really shouldn't exist.
I agree that sustained bad feelings and anger are bad for anyone. But I know many who leave JW's are surprised to deal with the world on a different level. It's tough out there. Being a JW doesn't prepare you for that reality at all. So when I read of hot headed opinions, and people getting upset because (surprise!) people disagree with them, there is another lesson that is learned. Don't expect everyone to fall over for your thoughts. You've got to earn your way in this world, and the fact that you show up with your mere presence isn't enough to change anyone's mind.
To me, these debates reveal those who have at least thought through some of the issues and can explain them on some level, and those who inherited them from others, and want to parrot what they hear without giving it due thought, as a responsible citizen should. (both sides politically)
Religiously, the theistic debates that go on are just as important, for obvious reasons. Former JWs have a ton of stuff to work out on the whole god/worship question. No surprise that arguments will sometimes occur.
I do agree though, that a more civil, less hostile tone, could be taken by many. There are times I have failed in that, although I try my best to be civil. Sometimes I fail too. Still trying to improve there.