It's actually important to stay alive as a DPS as well, especially in a EX trial or savage raid. The spotlight might not be directly on you like a tank, but dropping to the floor is a serious DPS loss which could make the difference between whether or not the group can skip a phase depending on how the fight is set up. DPS and healers are targeted by mechanics a bit more frequently than tanks, if not a lot more.

Ultimately, it comes down to what you enjoy playing more. If you feel like DMG is the best way for you to contribute to a raid, then play DPS. But avoiding KO status is something all three roles have to worry about. If you do decide to keep tanking, and you feel panic starting to set in, remember to just breath. Deeply though the nose, slowly out the mouth. This has helped me tons when doing first time encounters on my DRK.

Good luck out there!