We had a SWO in my reserve unit whose first JO tour was on the USS New Jersey in the late 80's and he said while it was as awesome a tour as one might imagine the material condition of the ships was extremely poor and they could not have stayed in service much longer than they had. Given the way they were built, with the extensive 'all or nothing' armor and without much consideration for future upgrades, it would have taken much more work to refurbish them than more modern ships. Think of a mid-life overhaul for a carrier but even more extensive and on a hull that no one in a shipyard had first-hand experience working on for almost 50 years by the 80's-90's.
The comparison to the B-52 is also a fallacious one, with aircraft usually having been operated for only a fraction of their total lifetime and usually being maintained to a much higher standard overall. It also helps that they have been maintainng them continuously since they were introduced into service and the original manufacturer is even still around.