Production shows, from inception to completion are multi-million dollar productions. They also have high ongoing costs to run, this is why they do not have a high turn over rate.
I'm not a huge production show fan. I have seen a few repeats "Bond Voyage" was on Mercury and Millennium. I may see some of them but in the end it usually isn't my cup of tea. My wife enjoys them and will elbow me in the ribs when I fall asleep.
I prefer a comedian, or individual performer.
However, they are a big draw for the cruise lines and they keep investing in them and they are constant favorites by the guests.
One last point: "Most" cruisers don't cruise, often enough, to have the opportunity to see the same show again.