"The flight time leaving DAY does make sense for making a same day cruise connection. The flight time leaving MIA does not make sense for returning cruise passengers. One's off the ship by no later than 10:00-10:30 A. M. A 9:30 P. M. departure from MIA would not be desirable. I have no doubt that AA's market research does show sufficient demand during the Fall and Winter for such a flight to MIA if cruising does return late 2020 or early 2021."
The late night flight is a catch-all. It's less important to connect the cruise passengers home... than it is to get them to their departures. On return, if they are off the ship in the morning, there are many connecting options to get them home sooner. When stuff happens, weather or whatever, having a late night nonstop to get people home is useful. Traditionally these late night flights protect the misconnects and the nonrevs who have been unable to board a flight earlier. By that time, normally there are not a huge number of people to be stranded, so if the late night flight cancels, not too many people who have to stay overnight and try again in the morning.
Of course, there are hell nights such as rolling thunderstorms in Miami where a multitude of flights are affected and the experience becomes the stuff of people saying "I will never fly XX again" which goes out the window at the next fare sale.
The late night flight is a catch-all. It's less important to connect the cruise passengers home... than it is to get them to their departures. On return, if they are off the ship in the morning, there are many connecting options to get them home sooner. When stuff happens, weather or whatever, having a late night nonstop to get people home is useful. Traditionally these late night flights protect the misconnects and the nonrevs who have been unable to board a flight earlier. By that time, normally there are not a huge number of people to be stranded, so if the late night flight cancels, not too many people who have to stay overnight and try again in the morning.
Of course, there are hell nights such as rolling thunderstorms in Miami where a multitude of flights are affected and the experience becomes the stuff of people saying "I will never fly XX again" which goes out the window at the next fare sale.