Slow descent, I may be wrong but I get the impression you haven't been flying as a professional airline pilot for that long. Couple of years maybe? So you may not have been 'bitten' by fatigue yet. One day it will happen to you, make no mistake. Our days are long and tiring. As you get older, it becomes even harder. And the extra task of being in the left hand seat makes it even more tiring. The FTL's are supposed to be absolute limits, not the norm for every day!
But don't try to turn it into a safety issue when it's nothing more than "working less because we fancy it". And don't tell me BA pilots are an efficient work group when they could improve their productivity by over 10% simply by working up to perfectly safe legal limits.
You don't really believe this, do you?