I'm sure it was a tactical decision. But there's no reason to dissociate Rumsfeld from the operation, other than it demonstrates a known problem with his intention of replacing artillery with air power.
Rumsfeld is not the first SecDef to emphasize a cost/benefit ratio. That was precisely what McNamara was known for, along with a goal for "modernization", and it's why some critics see Rumsfeld as McNamara redux.
Modernization isn't always what it's cracked up to be. There was once a decision to eliminate guns from fighter aircraft. After all there would be no more aerial dogfights. Until there were, and we needed guns and Top Gun training. Some generals are certain that in a future fight we will wish we had effective artillery, despite the fact that they won't ever be needed again, just like guns on fighters.
Rumsfeld just didn't buy its replacement.