Yeah, as much as I enjoy getting to use all of those extra units in the campaign, it seems like the difficulty balance is off now. All of the enemies are scripted so that they are never aggressive and never retake requisition points or power nodes. And you nearly always have so much requisition and power that you can keep respawning your army indefinitely. As long as a one of your units escapes death when an engagement doesn't go your way you'll be fine. And that's very easy to do with the increased units and the ability to recall heroes from structures.
I guess they should have gone the CoH route with a single player campaign that follows the rules of multi-palayer, and features aggressive AI vying for map control