I totally agree with you Paul. We are shortly doing our 6th and 7th cruise and entertainment plays a huge roll of one's lasting impression of the cruise ,as doezs cuisine ,sevice ,ports visted ,excursions ,cabin etc .What I am saying is that they should understand that they are selling an experience and not a cruise. The better the overall experience the more referrals and repeat business they will get -it is as simple as that.
We have allways found the entertainment on cruise ships mediocre,especially the shows and seldom go to these anymore -and why does the Entertainment Director always have to perform? they are normally not very good.Some entertainers and orchestras in the pubs and public areas were ok to good, though.The ice skating show on the Oasis of the Seas was brilliant.
There are a lot of really brilliant artists available in every country -ok they are not big names but brilliant nevertheless ,and not expensive.My advice would be to make an effort to identify these and use them . The crux of the matter is to look at each country and not just US and UK performers