> Plus the fact you can "record" them from a real-world physical environment without ever having to "model" it opens up a lot of utility too.

This is the big thing imho. Sure, you can do traditional photogrammetry to capture meshes and textures but getting the shaders exactly right is afaik non-trivial etc, and if you want real-time rendering then you likely need some further post-processing of the assets. With 3dgs you can pretty much bypass all that complexity and the whole pipeline from photos to rendered frame is much more straightforward.