It really shouldn't be much work to do that if the database is set up correctly, IE a character info table is linked to an account table. You'd simple change the account ID that this character belongs to. Nothing needs migrating on the back end, just a value changed in the character info table to make the character show up in a different account. One developer could turn that into an easy to use process in half a day.
I'm sure SE have other reasons for not allowing this kind of transfer however.