Body armour remains uncommon until recently despite China being a significant exporter of body armour
As to your second point, it’s a matter of doctrine and perception by the PLA. Doctrine as in the PLA still seems to be trying to figure out what it wants to do with the new helicopters. Perception as until very recently body armor was less a big deal. As were things like armored support vehicles (MRAPs
I mean it’s 2020 now. In 2000 the US introduced the Interceptor vest by 2003 although front line troops had the type in significant numbers, reserve and national guard units called in as support troops didn’t. By 2007 US forces were starting to replace the interceptor series with newer more effective systems.
prior to the Interceptor system wide spread infantry level III body armor was virtually unheard of.
Standard was body armor rated to fragmentation. At max it might stop a pistol round but that’s a stretch. Now that’s the US so.
So look at China prior to 2000 they were still working on equipping modern rifles let alone armor.
take that to the 2010 period. In 2011 we get first reports of modern ceramics but what’s the need? The US was at war that drove rapid advancement and need of fielding. The counter insurgently drove armor issue and development for NATO troops more by need. China wasn’t In that position.
Move ahead that 9 years they improved the design refined materials but the cost to fit every soldier would be extremely high. I mean the PLA is over 2 million. Not all are combat arms or front line So why waste money? What they do is order 1.4 million.