To illustrate a bit the problems staffers face when working on force structure changes, I can relate my own experience as a bit player in designing a Stryker Division - that is, a division element controlling three Stryker Brigades. This never came to fruition, but the boundaries we were given at the beginning of the process were as follows:

1. A manpower cap - I can't remember what it was but somewhere around 12-15,000.
2. Deployability - the whole division had to be deployable by air given so many sorties in a certain amount of time.
3. No post in Alaska or Hawaii could have fewer soldiers on it at the end of the process than they currently had - a politically imposed condition laid on in deference to the powerful senators from those states.
4. USARAK had to maintain its airborne capability.

Cost (in terms of dollars) never really came into it. But these are the kinds of things that cause otherwise intelligent organizations to do stupid stuff.