I think Disney Cruise Lines must stay with the in-person muster. Their primary customer base are families with small children. The ship's crew NEEDS to see that the parents take the drill seriously enough to know how to properly place a life vest on their kids, then know where to bring them in an actual emergency.
As for the others, yeah, their decisions are probably related to the bottom line. But then I have to ask why is NCL going back to the old method? If any decisions are made to enhance the bottom line, it should be theirs. They are the one of the big three who faces the greatest risk of bankruptcy.
There seems to be a general agreement among the people in this forum that the new style muster drills are a joke, and the only reason people like it has nothing to do with enhanced safety but everything to do with enhanced convenience.
Is Norwegian Cruise Lines decision to go back to the in person muster drill an act of good corporate citizenship? Do they recognize the fact that in the event of an actual emergency most passengers (especially newbies) won't be able to glean much from the new style drills, so they chose to go back to the old methods to promote safety over the bottom line? Although I find that hard to believe, I'm lead to wonder.