Arcology thinking stands in opposition to the “a man’s home is his castle” principle. That can take the form of centralized authority, or of “we’re all in this together” cooperation.

I think part of it is that arcologies are an example of the classic “if this goes on” trope in science fiction. We keep building bigger buildings in our cities, and building bigger cities, so it’s natural to ask where that will lead us. Arcologies are one of the tourist attractions along that path, then the ecumenopolis (like Trantor), and then on to the megastructures...