DCL knows what families do and don't want to deal with on their cruises. Reserving pool times & trivia times are anathema to most guests, who just want to relax and do what they want when they want to without being overscheduled, which is one of the things that makes a cruise much more relaxing than the Disney theme parks, for example. What DCL has to do to get through the initial phase of cruising this year isn't the same as how they want to run things going forward next year and onward. Changing an app isn't that hard for Disney. There is no reason to assume or preach that "this is going to be the new normal and everyone had better get used to it". There is no indication of that at all. It's clear that the UK sailings are going to be unique, and everyone knows that cruising will be different during the initial reopening period until the CDC stops micromanaging cruise lines. But beyond that, DCL is going to focus on getting back to normal and making their customers happy.
I'll also add that America and Britain are in very different places in regards to reopening & people's access to vaccination, and therefore in regard to how much freedom they're accustomed to having. So a restriction that might seem like no big deal to someone living in Britain right now & is accustomed to Britain's level of restrictions, would seem much more restrictive to someone from Florida. And Disney understands that. They don't have to deal with Americans on their UK cruises this summer, but their later cruises in the U.S. will have mostly American passengers who aren't going to want to pay to be micromanaged on vacation. A large percentage of them will have been sending their kids to in-person school almost all year, have been able to travel domestically with very few restrictions, every adult here has the chance to get vaccinated, and it's gradually becoming available for their kids, too. They can go to Disney World and walk around maskless outdoors at the parks, and go from ride to ride at will, eat at restaurants, then hang out at the resort pool when and how they wish. They aren't going to want to then board a
Disney cruise & feel like they have to schedule their every move.