I'm sure a good set of radios would work fine, but for me, I personally don't want to be bothered with them. I have kids and have taken kids on a cruise. We just made sure we knew where they were, what they were doing and who they were with. Then from time to time would check up on them. The ships are large but you don't have to taxi to get to the other side. We had no probelms.
Not only have my packing habits changed but they have changed due to my plans while on ship or in port. I have cruised enough to be satisfied with not doing everything the ship has to offer and so I don't have to pack as much. I spend most of the time in swimming attire anyway so i figure what's the use in packing all that "might need" stuff.