Its just like the dilemma PLA faces with scopes. We have seen regular PLA troops exercise with magnified scopes on their Type 95 rifles and some have even started exercising/trialling red dot scopes. Without doubt these assets can significantly aid the PLA soldier's ability to fight and shoot accurately at longer rangers (or acquire targets quicker at shorter ranges). But just like NVGs, the PLA cannot afford to equip every Type 95 with a scope/sight.
The same argument can be said about body armour.
I'm sure in time of war however, things like NVGs, scopes and body armour can be produced relatively quickly. Perhaps PLA has only sufficient numbers of all three to ensure that most if not all PLA regular soldiers will have the opportunity to train with these combat aids, therefore there are only enough of them to go around for training purposes. So as long as PLA troops are trained to use these aids, it doesn't really matter whether they currently have them or not. Its cheap and economical I know, but nonetheless it is the best compromise between not having them and having too many sitting in the closet gathering dust while costing Chinese tax payers disproportionately.