I think heroic 5-man bosses, at least in the new ZA and ZG heroics, should have an ability that wipes the whole party if someone messes up. I mean look at Ozruk (sp?) in Stonecore for example. He can wipe someone, but even if you get a couple idiots killed by it the tank, healer, and a dps can finish the guy eventually.
Now there have been tons of times in a heroic someone messed up and died basically at the start of every boss and when I try to kick I hear, "dude it's a heroic don't be so serious." If instead of just dying himself, that guy got the whole group killed and threatened their chance of finishing the dungeon, people would be held a lot more accountable for their actions.