

Some things off the top of my head are:
- you could set the temperature to a number of degrees via a numerical display, which would be much harder to implement without a microcontroller.
- maybe you could have PID control over the compressor rather than bang-bang control, so the temperature would be more stable.
- these days, a bimetallic strip costs more than a microcontroller and a chip thermometer, despite the chip being much more accurate.
All of this only requires a really dumb microcontroller, though, not one with networking. I don’t see how that could be useful until your fridge could magically track what it contains so you could ask it if you needed to buy stuff while you were shopping. I don’t think we have the technology for that yet.

Image recognition will be able to figure out the obvious items, and hopefully the expiration dates, too, but it’s not going to be able to figure out that opaque containers are nearly empty or identify leftovers in tupperware. It’s also probably going to be unable to identify when loose produce is past its best unless it’s extremely rotten.