Agree with the OP, as a WHM if the DPS keep doing such a thing, i just let them die until they have understood they're not a Tank.
It sometimes takes 2 or 3 times before they get it. I don't care if they rage at me in the process, learn your place and everything should be fine, Tank and Healer always run the group not the DPS.

My priority is ( in order ):
1. To keep the Tank alive.
2. To keep myself alive so i can obviously keep the Tank alive.
3. DPS, when they are legitimately needing heals.
4. Pets, if i want to. Even tho it should be the SMN/ACN/SCH responsibility to take care of this.

My job is not to keep some impatient DPS who think they can Tank, alive.