While is nice new feature, is kind of unrealistic (weight of neck) and immersion breaker to see everyone with NVG mounted in the helmet in the middle of the day.
It is possible to mount them only under some condictions (like diver's googles) such as:
(close to) nightime or when the user switch them off and they became idle for x amount of time.
It could also prevent some clipping like the one that happens when flying the A\MH-9.