I would think the argument for this is that it would enable and facilitate more advanced environments.

There's also plenty of games with fully explorable environments, I think it's more of a scale and utility consideration. I can't think of what use I'd have for exploring an office complex in GTA other than to hear Rockstar's parodical office banter. But Morrowind had reason for it to exist in most contexts.

Other games have intrinsically explorable interiors like NMS, and Enshrouded. Elden Ring was pretty open in this regard as well. And Zelda. I'm sure there are many others. TES doesn't fall into this due to the way interiors are structured which is a door teleports you to an interior level, ostensibly to save on poly budget, which again, concerning scale is an important consideration in both terms of meaning and effort in-context.

This doesn't seem to be doing much to build upon that, I think we could procedurally scatter empty shell buildings with low-mid assets already with a pretty decent degree of efficiency?