Yes, I have. There was this one boss in TBC named Lady Vashj(you might have heard of her). Multiple paladins were required to keep the MT moving freely away from the poison puddles.
I can definitely understand your point. Comparing how many times I would be inclined to do one or the other, I will cast Hand of Salvation more than I am willing to blow all of my Holy Power on someone else. We clearly don't know how things will turn out, but that's my take.