Is it really a good idea to unite everyone behind the humans? I think it depends on what you think the stakes are. I was still carrying around ideas from Mass Effect 1, where the Reapers were an unstoppable, implacable foe that had done this hundreds of times already. Beating them conventionally is a ludicrous hope, so our goal is to fight them as best we can. Remember, in previous cycles they killed everyone, down to the very last being. Empires of billions of people on hundreds of worlds were driven to complete, 100% extinction. If even a handful of people had survived they would have repopulated. You can’t beat these guys with zap guns, which means you’re just trying to last as long as possible, not “take back” conquered territory. That should preclude large offenses.
Here in Mass Effect 3 the characters are fighting to save Earth. It’s hard to tell how we’re supposed to read this. Has their power level been retconned so that beating them conventionally is possible? Is Sheppard supposed to come off as a sad, self-deluded fool who can’t accept the truth that his homeworld is toast and so he’s dragging the rest of the galaxy along with him on a foolish plan? Is this supposed to be a diversion so we can finish building the crucible? (Does the game ever say where it’s being built?)
I don’t know. It’s kind of an important point, since the whole game is spent on this “take back Earth” deal, and I couldn’t even tell if Shepard was the dummy, or the writers.