If a DRK casts blood price and you can't wait 4 seconds for him to get aggro and manage MP so you can easily holy spam, then your just making things more difficult for others.

Healers were made to be able to DPS easy, and they balanced around that. Mobs hit harder and tanks have less mitigation... you can't dps as much as you used to.
If any DPS or tank dies while your DPSing, the loss of damage because of that is greater then what you will pull. So DPS, but don't make things harder by forgetting people in general take more damage and tanks can't just absorb as much damage anymore. Should people complain to you about this? No, not really unless you are killing the group.