Those infinite layouts are still bounded by something physical. Steel stud framing isn’t difficult to install and remove but it is still anchored to the floor. That means you have to remove not just the wall but also an area around it and carefully redo the finish so that it matches the high quality floor finish required of a truly trackless ride system. Gypsum board (drywall) is also not difficult to install but using it for a projection surface requires actually achieving a Level 5 finish (on a scale of 1-5). That’s a lot of intensive labor just going into temporary walls.
Moving a wall is also not something that can just be done as art direction. It will require an architect and engineers to design and approve, pushing the whole attraction through the building permitting process. The wall moves also have to be coordinated with all of the stuff in the ceiling like the HVAC system, fire sprinklers and lighting. It is possible to build walls that are not as tall and avoid some of those systems, but that means more anchors into the floor. Set pieces only add to all of that work. They have to be anchored into that nice floor. If they have any sort of movement or lighting they will need power that is coming from somewhere.
When all is said and done, how much less work is that than a permanent attraction? How is the Studio going to be convinced to keep funding all of that work for subsequent films?