The Modular BCT's were a derivative of MacGregor's ACR concept. That concept was way too expensive for the Army to ever afford, so decisions were made as a compromise to capture the combined arms nature of the ACR. Even after the initial drafts of the Modular BCT's were examined, there was an issue with the costs associated with the BCT's.

Then an "either/or" scenario appeared. The Army was forced to decide between BCT's with three infantry/combined arms battalions and a recce squadron, which would result in X number of BCT's, or they could accept a two infantry/combined arms battalions and a recce squadron and have Y number of BCT's. The Y number resulted in more BCT's - which is why it was accepted.

There have been rumors floating around for a year or so now about returning to the three infantry/combined arms battalion structure. If enacted, it would reduce the number of BCT's to the X level mentioned earlier. There's no such thing as a free lunch when it comes to force structure.