I don't like that it's on the port days which is one of the main reasons people cruise.
If they did it at say 1pm on embarkation day and gave those attending boarding priority at 11am I would be more likely to attend. Then you kick off your cruise with a bang rather than not be able to do a tour in Mexico because the concert. Also it seems it would be cheaper/easier to fly in guest entertainers to US ports saving a bit for Carnival.
11 cruises in 2012, 90 nights at sea visiting 15 countries
8 cruises in 2013, 56 nights at sea visiting 7 countries
Next cruise: None scheduled
PM me if you need a cruisemate for any Europe, transatlantic, or Panama Canal cruises
Date, ship, cost pp