The B1 trades rugidisation and capacity for speed.
The B21 trades them for stealth.
B52 is optimal for mass bombing. It’s shape makes spares, repairs and production cheap. It’s optimised for bombs/$ via mass deployment. The B1 and B21 could fill the role, but not as well. They are optimised for other uses (B1, get in fast, smash a target and get out. B21, sneak in and pummel a limited target.)
That being said, the last time the US needed that capability was likely Vietnam eta (leveling large areas of jungle). Having it available is still militarily useful.
Poor wording on my part.
The B1 trades rugidisation and capacity for speed.
The B21 trades them for stealth.
B52 is optimal for mass bombing. It’s shape makes spares, repairs and production cheap. It’s optimised for bombs/$ via mass deployment. The B1 and B21 could fill the role, but not as well. They are optimised for other uses (B1, get in fast, smash a target and get out. B21, sneak in and pummel a limited target.)
That being said, the last time the US needed that capability was likely Vietnam eta (leveling large areas of jungle). Having it available is still militarily useful.