Each of the 24 missiles carried, have 8 independent warheads, allowing for 142 targets to be sighted in on. Show me where a B-1 Bomber can deliver that amount of firepower, and survive like a Trident Submarine can.
Yes, that's why they were used against Saddam Hussein... oh, wait, they weren't.
Horses for courses, TridentDwarfman. The Ohio class submarines can be used only in nuclear war, unless converted to other purposes. Replacing the B-1 with them is fine, if you want to be involved only in nuclear wars - I can't remember a politician that has that position, though.