As Canadian ex-pat retirees who now travel for pleasure and strictly at our own expense, my wife and I cannot fault BA regarding this!
It is certainly preferable to the insidious fuel surcharges so prevalent nowadays and is far more likely to hit the leisure traveller harder than the business traveller.
For cost purposes we shall just add an extra 120 pounds sterling to each return YYZ-LHR fare in calculating the total cost before deciding which carrier/gateway to use.
However, the really big impact is on RTW ticketing where BA is the actual carrier for multiple segments.
There are some seniors (like us) who simply will not make a reservation with any carrier who does not provide seat select AT THE TIME OF BOOKING.
So, we thank BA for implementing this. We now have a greater likelihood of flying BA if the price is right.