The battery is the most expensive part of the vehicle. It can be swapped, but is the biggest price item in the vehicle.
Battery swap robots existed 6 years ago so it's possible but the battery has an 8 year warranty so it's literally not a concern people have.
I think it is important to offer a choice.
Elon has already stated many times it's coming as a choice but right now the only sane reason for a battery swap is if the battery fails which is covered by warranty.
