EASA has absolutely no basis in common sense. I think everyone accepts that?
However the back to back restrictions may at least have been partially based in a desire to protect folks from themselves? For example, the back to back to back to back to back merchants. Who have commuting/UK income tax issues.
It's also the case that many in BA, don't like back to backs. BA MAY have allowed them, (as they do for cabin crew) had they been given a free hand to impose them on all.
My personal view is that the current arrangements are about right?