Again, trash mobs do not hit hard. If I can 3 man the majority of the hardest dungeon in the game without a tank in the party that says it all. If you're that bad of a healer that you're only willing to spam 1 on your currently selected target then that's your own issue. When I am rotating Fire II to kill trash quickly I expect to get hate on one of the mobs if the tank hasn't distributed his enmity well enough and it is never a problem. Tank claws back the mob as I switch to MP regen, healer tops me up and I go back to DPSing. I am not going to artificially give myself a 5 second GCD just because you suck, I just won't party with you. I don't improve my gear just so I can cancel out all benefit it gives by holding back my attacks a second or two longer. I may as well just join the party in full AF if you're that bad and DPS as normal. The DPS parsing would be the same.
The point is, if you are a smart DPS and know your limits then taking a whack or two in the face isn't an issue. DPS are even meant to tank trash in some instances, IE the demons that spawn in the last boss fight of AK. If a DPS can't handle a mob hitting them then you aren't clearing it.