The "inherent reason" is that user freedom isn't allowed in SIM land, basically.

eSIMs are designed around "the user is the attacker". So you can't do things like transfer profiles from one eSIM to another offline, by design. What the "transfer" really does is kill the old profile and issue a new one for a new eSIM.

It still could be designed for less user friction. But the whole ordeal could be avoided if eSIM wasn't designed to be user hostile in the first place.