I am no expert on this age, but i think the divisions and brigades used on the American Revolution lacked the permanency and staff organization to consider them "brigades" and "divisions" on game terms and use the same system used for them on the AACW.
On AACW game brigades are permanent (elements can't be separated) an divisions, while not that permanent, have big benefits on command points.
I think that advantage try to simulate the staff and logistic organization of the division which is more important than the "ad hoc" SXVIII division formed just for one battle or campaign. Probably, latter could be better simulated by normal stacks.
The probable % penalties of this stacks for lack of command points can also reflect the problems of command and control leaders of this era had, commanding a less structured force that the ones developed on later years (Napoleonic, Civil war...)
I think the new game should have some kind of system to avoid the huge and disorganized "death star" stacks one could make on the first game, but i´m not sure the system used for the ACW and NCP could be used here as it is.
I´m sure the developers are working into something...
Just my 2 cents