One of the other things that more finely-grained monitoring can do is to help let you know if/when your appliances might need service before they completely break. Like if the load in your refrigerator suddenly spikes because the compressor's going out, you can call a tech out to take a look at it before you come home to a house full of spoiled milk. Or for your air conditioner, you may want to schedule to get the ducts cleaned because there's a clog somewhere. There are quite a few little things that this sort of monitoring can help you with and save you money.
That's quite common for commercial HVAC gear. There are lots of commercial HVAC units regularly sending pager-type messages to a maintenance service. Again, that's been around for years.
Wouldn't it be more sensible to put that into the appliance itself? Detecting at the endpoint seems more reliable (since it's not mixed with other devices, and can be calibrated to the specific model) and private, and while it requires some redundancy in sensors, it avoids the need for a complex monitoring network.
