The only compelling reason I can think of is: If for some reason charging technology is unable to be improved to the point that it's comparable in time to fill

The only compelling reason I can think of is: If for some reason charging technology is unable to be improved to the point that it's comparable in time to filling up, and if for some reason the solution is to go back to the idea of battery swaps. I could see this being reason enough to keep the whole system as rentals. If I'm an owner, I'm going to think twice about swapping out a part that might be 50% of my cars value. There would need to be some serious quality assurances to make that work.