"pressing the issue is like arguing that our soldiers on the ground should be issued Garands"
Not really. The question of their obsolescence can only be answered if you first ask and answer "in what role?"
Surface warfare? Ironically, not completely, but ships don't kill ships anymore, unless someone really screws up somewhere. Aircraft kill ships. Submarines kill ships. Ships do not go toe to toe with ships anymore. An
Iowa would be at the core of a battle group that would preclude her ever coming close enough to have a surface action. However, if something went seriously sideways and it were to happen, she'd fare well. Her armor is proof against missiles of the not fission/fusion variety, and her probable offensive weapons (Harpoons) are as good as anything else in the fleet. If stuff got really close, sure, she could open up with the guns.
The thing is, though, you have a ship that is, offensively, as powerful as a destroyer or cruiser, and is much more expensive and valuable...and all of this for a scenario that just won't happen.
Command and control? She's fine as a command ship. So are lots of other ships that don't cost nearly as much to operate, or that can do other things (carriers, amphibs). Coordination of air defense? Not without multi-billion dollar upgrades. Coordination of sub defense? Same deal.
Support of land forces? She is still a viable option, and is in some ways better than anything else out there. Using her has a missile platform is fine, but again, she's no better offensively than any
Spruance class destroyer. The only arena in which a BB is better than anything else out there is in naval gunfire support. In that, she is waaaaay better than a cruiser toting dual 5" guns. And her loiter ability is better than air support. And if a missile battery on shore does open up, she won't miss a beat.
The REAL question is, are BBs worth the truly frightening expense to operate and maintain in order to get the advantage they offer in that one, narrow role?
The Marine Corps says yes, but the Corps isn't the one footing the bill. The Navy is. If the USMC wants her as gunnery support, let the USMC put her on their budget.
One last thing: the fact that she isn't set up for anti-air combat or anti-sub combat isn't an issue. She would never, ever operate alone. Modern naval warfare is a team sport.
Mike