As others have noted, the original suggestion that BA Holidays should provide this facility is not a sensible suggestion or ever likely to occur in this universe. IAG Loyalty is driving this change and is doing it to try and tap into the lucrative commission fees from hotels and car rental companies. They are doing it for their benefit alone not the customers and like most things IAG do they will cheapskate the IT, minimise resources and look for the lowest cost options whilst providing the minimum of service to the paying customer.

On a practical level, I have looked at whether going the BA holidays route is feasible for certain holidays that we take. When you do this you see that the range of hotels offered by BA Holidays is woeful, particularly if you stay in 5 star hotels. This rules BA Holidays out immediately from lots of locations. I did manage to find one location which we go to quite frequently and the price comparison between booking flight separate and hotel direct versus using BA Holidays yielded the following .
Price of flights direct with BA = £10,854.
Price of Hotel booked direct = £9,956.31 which incudes $121 buffet breakfast every day, $400 resort credit, no resort fees ($412.50 saving) plus points on total hotel stay plus incidentals.
Total cost of holiday £20,810.31
BA Holidays price for exactly same flights, hotel, room etc = £22,829 which includes loss of hotel loyalty benefits outlined above.
So in this real life example BA Holidays works out just a smidgin under £3,000 more expensive for less.
Good luck to BA Holidays trying to sell this to customers.