The huge application for this I think is video games. Instead of having to create every small detail by hand, you can just create the space in real-life and then have that rendered.
Somewhat ironic but for a certain type of person its actually way easier to throw together a simple set than to build convincing 3D art. Once could imagine a point and click adventure built this way but I wouldn't expect that is really a major use-case.
That said, the more general aspect of "accessible, user generatable content" is a better way to look at it.
Can’t tell if that’s a joke
Ironically this is currently very ill suited to gaming. (However, I personally think there's plenty of use cases beyond gaming. Including "it's just intrinsically cool to be somewhere that no longer exists")