The typical JR/Futaba/Hitec connector is not a very high tech piece of equipment and always have permitted some amount of pin movement. Other areas of small aviation recognized this a long time ago and either corrected the problem with a method of preventing pin movement or changed to another type of connector. Better connectors cost more money, and even a few pennies can make some people squeal, so they have remained what they are for decades. As previously noted, one engine manufacturer tried to provide their customers with an excellent connector but the customers weren't smart enough to recognize the better mouse trap.