Just to be clear, VIT have nothing to do with surviving pulls.... if he is dying from 3 adds, his mitigation is the problem, not the lack of 10k~ hp from not using Vit Acces
Just because mitigation is important doesn't mean max HP stops being important. It's also a critical factor. If you ran into enough healers on the DF that don't have the greatest reaction times or are otherwise seemingly keen to let you drop to low health before doing anything about it, you'd know this.

Personally, for a pull of just 3 mobs, you shouldn't even have to be using much in the way of mitigation, so I'd say this is due to either massive undergearing on the tank/healer's part or the healer not being attentive.

For me, when I'm in a party I know is capable of handling a larger pull (as in, I know they'll actually AoE and won't take forever to kill doing so), I may do a small pull *because* my good CDs are all down and I don't think a larger pull will be survivable in my current state, and I'm using that as a means to get them back for larger pulls.