The Devastator does 245 damage to ground targets per shot (367.5 with the Double Time Upgrade). Either is the most damage for a land-based unit (The Juggernaut and Bomber Balloon outclass it though, but are more expensive and more vulnerable respectively.)
I can play with it some more, but even if you're right and it isn't do a lot of good for units, the Devastator has a critical role in cracking enemy turret defenses.
