Axx, I expect it was a regional issue. In the Northern Rockies the 25-06 has been a very common caliber going way back. The .25-40 Krag in both "Short and Long" was considered to be a good choice for the Northern Plains.
I owned a beautiful .25-40 Krag long on a Krag action. I never hunted with it but it was a fun old rifle to shoot.
The larger 25-06 was deadly with the 117 and 120 bullets on Big Mule deer and elk in open country. Our local outfitter and gun store stocks over 1,200 rifles. There are no .257 Roberts but there are .257 Weatherbys and .25-06 rifles. It is that old reloading custom. You can always load down a larger case but loading up with a short case is limited.