Color me skeptical. I'm unconvinced. In fact, I'd bet money that RPG's are the "driving" force behind our recent uparmoring.
Of course armor has a trade off. But the main rationale against it was deployability. We went with specs that required deployment in 72 hours by C-130. As a fact, we had nearly a year of diplomatic run up and are still there a year after the outbreak. The deployment specs had everything to do with forcing a lighter result and nothing to do with actual typical war conditions. And we are paying for it. Heavy armor has done everything asked of it in Iraq and we have succeeded at trivial cost every time it has been used. We aren't using more of it, more often, because budgeters don't want pay for the next generation of it, not because we can't operate it in Iraq day to day. In fact, uparmored HMMWVs have less off road ability and will break down more. And meanwhile, we are running scores of combat forces - not just supply people - around in open trucks. The Marines have 403 tanks on strength, force-wide. When they rotated into Iraq they brought 16.