I think that both powder and lead was very expensive back then and most of the hunting was small game in the eastern states. It don't take a .58 to kill a whitetail or a black bear. That's why the "Kentucky" rifle evolved into a smaller caliber and more graceful and slender gun than the German Jaegar rifles that the German gunsmiths that came here were used to building.
There were also a lot of smoothbores on the frontier, advantage, they could double as fowlers.
It wasn't until we started settling the West that the need for buffalo and elk rifles came about.