Room scale is a type of VR application, not an application itself. So when people say that room scale is better (or bad or a gimmick) I have to inquire about the specific application.
When talking about specific applications the argument becomes more transparent. For example, if I argue that Hover Junkers is better than a stereoscopic movie, or that Aperture Robot Repair is better than Elite Dangerous. Why exactly is one better than the other? Because of room scale?
The real argument about the goodness of any particular VR application should be about how convincingly it simulates the intended experience.