Home Decorators Collection . . .
The basic idea would be to separate out all the functional components that go into a house (heating/cooling/ventilation, plumbing, electricity) from the insulation and structure, and to further eliminate interior walls except as needed to separate heating/cooling zone (leaving support pillars as needed).
Interior walls could be formed out of much cheaper and easier to work with materials (even fabrics!), and could be changed much more easily. The same would go for the utilities, plumbing/electricity/HVAC, they could be moved around and updated or repaired much more easily. This would be the real value of the setup; it would allow experimental interior designs that would otherwise be too costly or risky to be worth trying.
Almost anything you can think of would be far cheaper and easier to do in a home set up like this. As an example, consider installing an indoor fountain. Normally this would involve at least partially tearing down multiple walls to run plumbing and electricity and the floor covering where the fountain will be (and maybe to install a drain). And then of course all the work of installation, and repairing the walls and floor. In the modular interior system, you could avoid 2/3 of the work!