Purrsonally, I'd be fine just having the illusion of exploration.

Scarlet Monastery in oldschool WoW for example. I went into the physical monastery in the overworld and then had four dungeons next to each other to enter, two of which needed a key from the library. That "felt" like exploration, even though in truth all the dungeons were largely linear corridors. The dungeons still felt like part of the whole, something that's completely missing with Alexander for example.