Ausir said:Even in Van Buren the BOS stopped being isolationistic and instead waged war against the NCR.
You know damn well that design decision was made to stop the rampant growth started in Fallout 2 of NCR and BoS, Ausir, the Van Buren people chose that plotline because a major war between two powers would effectively toss the world backwards in point of development, rather than having it steam forward towards recovery like in Fallout 2. The expansionist BoS is just a plot device there.
Besides, there's a big difference between the Mid-West and the East Coast, in expansionist terms. Overstretch? Too big an area? Definitely, there's no way the BoS could develop the kind of institutional base needed for that kind of expansion from within 200 years of Fallout 1.