Hi Frase, glad to see you back. I definitely hear what you're saying. I think most every cruise line has the same problem. They have to schedule the "headliners" years in advance. The Legends show seems to be a hit all over the industry as well as in land-based entertainment venues. I remember the "old days" on board entertainment was normally Vegas style shows. Each line seemed to compete for stars (at least at one time). Usually one or two nights a week were actual movies in the theater. And one or two nights were commedy acts.
I know Carnival rotates their entertainment staff and I believe they change out their revues every 6 months.
It's hard to say how to improve it without spending a ton of money. I don't know how NCL is going to do it on the Epic. It has to cost them big bucks for Blue Man. They are charging for Cirque, but not a lot.
I'm sure there are loads of fans for the Carnival entertainment or they wouldn't keep coming back. I guess in a way, it's like home away from home, you know the tv schedule for the week