I think you misunderstand. BA is not protecting the integrity of the cabin - it is protecting it's revenue. You may not like this but BA are not doing this for fun or even to win a single customer's approval. They are doing it to generate revenue and, having done this for a little while now, they have ample evidence that the strategy works. You don't have to like it or even agree with it, your choice is whether you fly with BA or another carrier.