It makes sense to keep it, it doesn't cost anything to do so. They can patch it up from time to time and it doesn't matter how rubbish it is as long as it's 'exclusive'. People will keep using it and keep appreciating it as there is nothing else on offer in T5 to show it up.
To bring it into the general F lounge would really require an investment and overhaul of the whole floor which seems to be against everything BA stands for right now.