After dealing w/ many Chinese suppliers in various industries I believe the blame falls on the OEM. If you ask for cheap garbage then you’ll get that. If you ask for tightly specified designs that are properly designed for the process at a reasonable price then you’ll get that.
I’m w/ you on this assuming the question is: “Who needs it on their phone.” It’s the “on their phone” part that matters. It’s like…Who needs a can opener? Most people. Who needs a can opener on their phone? Not many people. The bigger problem being the can opener wouldn’t be as good as the standard tool & the price of the phone would increase. If I wanted/needed a thermal camera I would prefer to buy a dedicated device w/ high performance sensors.