In defence of BAE, when the project commenced we (I was at BAE at the time) told the MoD that it would be cheaper, quicker and easier to build new airframes from scratch rather than try to integrate the old fuselage to new wings.
"oh no, we want to save money by reusing the old fuselage".
"but that will cost more!"
"ah, but it's what we, the customers, want".
Seems like we've heard that one before.