Absolutely, ToW shines in Artillery Mode, as you call it.

My three little guys have it (well, Boylston does too when he's not Resto for certain raid events), and I only use it in two situations:

a.) I'm in an instance and relatively immobile while I pew-pew stuff down
b.) I need to kill a mob for a quest +3/4 levels above me

In outlands, most of the time I don't drop any totems while I'm out and about. What's the difference between killing the mobs in 2 spell volleys or REALLY killing them in 2 spell volleys? I will occasionally drop ToWs and some streams if I'm in a target-rich locale, but most of my time is spent running between very quick kills while questing.

When I use it however, it makes a significant difference. I wouldn't want to grind instances without it!!