Why don't other airlines, particularly those that have a higher service class up front
Derek
If you take a BA flight on a lightly loaded 767 around Europe, you will often find that the economy pax are allocated seats at the very rear of the aircraft, leaving only the Club pax up front and lots of free seats in between.
Obviously the premium pax expect to receive the service they paid for, which includes seats with extra legroom, so the computer seats them in the club designated rows and then moves the Y pax rearward to achieve an acceptable balance.
As the real Slim Shady says, it is often not so noticeable on other aircraft, although I do remember travelling on a Czech Airlines 737-500 where I was the only pax in business and all the pther pax were shoehorned into seats rear of the over wing exits. It looked very strange.