You're there to DPS and you decided that you'd purposely gimp your reason for existing "just in case" the tank sucked?. If I was the tank in that run, I'd have kicked you for harassment. Your spot would have been filled in about 10 seconds.

This is the same thing as a healer that tries to DPS while the tank is nearing death (DPS when you can, but healing is the priority) or a tank that tanks in his DPS stance. It's going to make the group more difficult and should be seen as harassment.