Not sure about the cost factor, but the Boomers represent a strategic advantage, since they are not as vulnerable as a surface ship.
A nuclear sub doesn't show up on enemy coastal radar, it just pops up and shoots.
IIRC ULCC ships shrugged off Exocet hits during the first gulf war...fill 'em up with, hell, bags of ping-pong balls and they'd be pretty tough to sink- mount scads 'n' scads of tomahawk missiles, a bunch of CIWS...maybe even advanced 8" guns...automate the hell out of it...slow, but somewhat less expensive, difficult to kill...
any navy types care to comment?
Possibly, but surface ships can be spotted by commercial satellites. Submarines are much harder to spot, so they can surprise their enemies.
It might be cheaper but the Boomers allow a whole lot of stealthy firepower in one package. Surface ships, planes and land vehicles are, potentially, more vunerable than subs.
It would certainly be cheaper to build a new surface ship to do this than to build a new submarine to do this, but as long as the submarines are already here and we're paying their operation costs and crews and support, etc., this might be a more "bang for the buck" way to use a few of them than to just have them waiting around for a full-scale nuclear war that may never come.