I specifically called out that the linguistics community says a lot of very reasonable stuff here, in contrast to the public. Are you disagreeing with me about the public? I'm not disagreeing about the linguistics community (except to say that there are definitely pieces of it that take a whole-hog preserve-them-regardless-of-their-own-good view of things).
The demand for monolinguistic isolation is real, and springs from the same realistic viewpoint you've stated that "the economic necessity will always win out". That you don't share it doesn't mean nobody shares it.
That's an interesting contrast! Language preservation efforts by professional linguists do usually have a lot of respect for the speakers' autonomy, where tourists' desire for things to stay the same so they can go see them as they used to be might be less respectful of local people's autonomy.
Of course linguists also have a scientific interest which isn't necessarily motivated by a view that it's good for people to speak their heritage languages, so much as that it's important for people documenting the language to have access to as many competent informants as possible (ideally also over time and from different walks of life). The ethical part as I understand it might be more like a desire for people to have access to the resources and circumstances that will let them become as competent as possible in all the languages they want to use.
The demand for monolinguistic isolation is real, and springs from the same realistic viewpoint you've stated that "the economic necessity will always win out". That you don't share it doesn't mean nobody shares it.