Perhaps the shortness of the polyester tie is because the assumption was that it would be tied with a simple knot? This requires less length of tie material than if a Windsor knot is used.
When I was at school, we were forbidden from using a Windsor knot due to the stigma still associated with the abdication 30 years earlier of Edward VIII (who invented the knot) and 'that woman', who became his wife after he was styled 'Duke of Windsor'. But as soon as we received a uniform at RAFC, the converse applied - Windsor knots were henceforth mandatory.
Nowadays a Windsor knot is the RAF uniform standard. But look at any of the Royals wearing RAF uniform and you won't see any Windsor knot - their tradition appears more important to the Family than being 'correctly' dressed.