I've not had the misfortune to be in this situation but I certainly agree that 'overbooked' and "We can ditch 14 at a stroke" sounds like too good an opportunity to be missed. You are certainly lucky that you were with (a large, reputable, up-market, British company) otherwise, you would still be on the banana boat.
This sounds like a loophole through which many others will fall as e-tickets become the standard.