For in-walled AP faceplates, I suggest not reading too much into them. They're more of the Wi-Fi/network commercial vendors trying to create a new business revenue stream out of nothing in China.
Here are a few pointers for your reference.
1) This is mainly for current big houses or SME offices with in-walled ethernet ports ready. Otherwise, 70% of the working population in tier-one cities rent a house or room.
Normally, those rented places don't have in-wall ethernet ports ready.  So, are the chances of your landlord allowing you to hack the wall and then install a new one?  *almost close to 0%*.
2) Even if there are in-wall ethernet ports that can be converted to an AP, their placement is likely to be super awkward.
They are either near the ground and/or covered behind furniture, etc.  Everyone who uses WiFi should know that placing Wifi units/APs higher from the ground is better than placing one lower near the ground.
So, in short, plug-and-play Wifi router/access points units (from Asus/TPLink, etc) nowadays are powerful enough (for most home users).   Otherwise, you can always explore POE ceiling top AP; it will definitely provide better coverage than that dunno-hide-which-corner faceplate AP la.
To me, all these AP in-walled faceplates are like adding legs to snakes imo 
