Yo, the dungeon revisits almost invariably owned. I think the only ones that were steps down were Pharos and Arboretum.

I don't even mind the reused areas because they're normally differentiated enough visually, and I think they gave a good testing ground for battle designers.

After Euphrosyne and a bunch of the Pandemonium encounters I think they could use dungeons to give some of the newer designers practice... (Referencing a JP article where YoshiP states that the new 24 mans were entirely within the hands of a newer battle design and story writing team)

Maybe it would be less costly to produce 'hard mode' dungeons again because the environments wouldn't have to be wholly new like with the separate Variant dungeons.