I usually leave when I end up 3 or 4 time in a row in a boring instance (like satasha or toto rak) or with another well geared tank in a main story roulette (no point having 2 tanks in CM or praetorium). Not because it's slow, not because of the other players in the group. Just because it's plain boring.

Instead of trying to force people to do boring content that I was already farming 6 month ago with my eyes closed people should ask themselves why players would leave these instances?