I believe the reason (assuming you were not being sarcastic and know this) is that BA had to pay a ton of money to have the door installed because before it, all passengers had to go down to the Duty Free level and access the CCR through the same entrance as Galleries North. It became kind of redundant when the First Wing went live as you can access it that way but I still appreciate it because I am normally accessing it through transit so not going through the First Wing.