I wonder if there's really that much of a benefit to AoE. Most times you're only fighting 3-4 enemies at once, and that includes archers and mages who won't conveniently ball up for you.
My personal experience is that If you deal with a group of demons, wolves (or whatever) your damage is much higher than a single shot.
I can't say what damage multiplier my bow uses, but it certainly works. I couldn't have drained so much health with higher damage single shots during the same time period. You can take that to the bank, as they say.
I don't know how things work for other weapons and abilities. I can only refer to the 'Explosive Shot' I constantly use with my bow.