USS Iowa lives!

Only five of them are "out of service" due to age

Although those were the first five ships in the class, the issue was not so much that they were a few years older as that they did not have the vertical launch system. CG-47-51 used twin-arm Mark 26 missile launchers, 44 rounds each, which cannot accommodate Tomahawk cruise missiles. From CG-52 on they had the Mark 41 VLS, 61 tubes each fore and aft, which offers more flexibility, reduced time between launches, and the Tomahawk capability.

Similarly the nine Spruance class destroyers without VLS were retired several years before their sisters which had received it.