It would definitely be a size thing for adding Ethernet (PoE or otherwise) to small boards like these. The ones I am using are already bigger than they ought to be - the bottom half is just a glorified serial interface and power input for USB. The esp plugs into this through pin/header. If I were less lazy, they could be about half the thickness in a final product. no PoE I suppose also keeps them cheap, which is always good for me. The casings were my first ‘proper’ design and entry into resin printing.

The Tapo kit I have found to be a good balance of price, features and quality. I have a Tapo C310 mounted outdoors at another building, which has done great in all weathers. Initial setup does require the app/service last time I checked, but it can be made to serve RTSP locally after that. Very good for the ~£30 price point.