Oh yes, forgot about the other reason for portability:
We have 32-odd aircraft in our hangars. Very rare more than half are flying at any one time.
So, as we do with fuel trolley for instance, maybe an idea to have some "club" transponders. Split/shares the cost.
Do we need registrations - well, yes, you can reprogramme. But, again, this makes more complex.
Keep it simple, make it cheap.
Think: what do we want things to do?
Unfortunately, all these committees are filled with people of a different mindset to simple leisure flyers.