1. Keep yourself alive through the aggro, and the tank should get everything off of you in short order?

2. Many dungeons are too easy. There are a fair few earlier dungeons in which Eos alone is enough healing, so why not throw out some DPS? Obviously, the DPS shouldn't come at the cost of party members dying.

3. If you ask, and people are willing to accommodate your request for a full clear, that is great. If you ask and the other three members decide against it, then why should your desire for the full clear be prioritized over their desire to clear quickly?

Edit:
Oh, there were more than three...