The gist of this whole thing seems to be "Rummy didn't/doesn't listen to us". The generals are thropwing a tantrum because their sage advice was not sought, and when offered, was refused, probably in a way that hurt their feelings.
That having been said, Rumsfeld is no friggin' genius here, either. It's my opinion this war was hamstrung from day one by the lack of ground forces to first overrun, and then, secure Iraq. We had enough ground forces to make a show against an Iraqi army that doesn't fight, but not enough to provide a big enough presance to keep the "insurgents" and "militias" in check.
Part of this is the general's fault themselves: Rumsfeld didn't cut infantry units during the previous administration. He had to fight and plan with what he had available, and if there were any professionals plannign the operation, they simply HAD know there weren't enough troops available. They probably protested there weren't enough troops, but were overruled by Rummy who was going to carry out the President's will. After all, that's his job.
Secondary to not having enough troops available, there was also the problem with getting Turkish co-operation in the initial invasion of Iraq, hence all this talk about "isolating our NATO allies". According to this train fo thought, if the original, professionally-cobbled together plan of invading from north and south (with inadequate troops) had been followed, we would have been successful, but that the State Department and Administration let the Pentagon down. That "inavde from two directions with an inadequate force" plan, supposedly, would have avoided 3,000 dead, if only Rumsfeld hadn't been there?
So, now here we are in Iraq and Afghanistan and having to face down Iran, as well, with no troops, and no plan of attack except to bomb the hell out of a bunch of places and no follow up to enforce our will or change the regime in Iran, and THIS IS RUMSFELD'S fault?
It is, but only according to six safely-retired generals, who presided over the vivisection of the US military, and some who now claim to have been "forced, against their better judgement" of contributing to the mess that is Iraq.
I'd say the generals are just as guilty.
The problem is not management at the Pentagon (vis-a-vis Rummy) but management of the pork spending (vis-a-vis get me some good infantry and screw 400 F-22's) and "wonder weapons" by the generals. An M-1 tank is a poor substitute for a platoon of infantry. No Apache is as versatile as an infantryman. No JSF is capable of thinking, improvising and processing information, and acting upon it, like a human being.
The mindset needs to change, all around; Rumsfeld needs to listen, the generals need to look at their own behavior and stop pointing fingers.
What would having more troops have done? Just more targets for pissed off out of power terrorist Sunni's. Make the case that it would have made a difference.