This is all fine and dandy as long as a few simple requirements are well understood by the technology implementers.
1) Legal liability for appliances and their cock ups is handled in much the same way as it is now.
If my toaster starts a fire and burns down my house, the insurance cuts me a check immediately while they handle the legal battle with GE (toaster manufacturer) and UL (Underwriters Laboratory who signed off on the device safety). The same legal protections for technology in appliances should be in effect. If my dishwasher gets malware (or just includes it by default) and causes my refrigerator to stop working and spoil my food, the insurance cuts me a check for my losses and to replace the defective appliances, and handles the legal issues.
2) Device interoperability needs to be as easy as antiquated analog systems.
You could hook up a TV with RCA or coax connections and be watching off a VCR or DVD player in minutes. It's ridiculous that HDMI is rarely so straightforward (it occasionally works this simply). Resolution, aspect ratio, audio stream selection, and DRM phone home setup is retarded.
3) Pick a device class to be the central hub, management, and gatekeeper. I suggest home wifi routers or a cheap, simple network bridge device.
4) Full control of permissions and actions by devices with simple to understand language.
If I don't want my washing machine downloading ads for Tide and Purex, it better f---ing not download ads. Same goes for usage tracking uploads.
5) Power usage should not significantly go up. If anything, connected devices should be able to lend clues as to how little changes can make my home greener and/or lower utility bills. Example: washing machine suggests running wash cycle at 8 PM to get out of peak usage billing. It sends me an SMS if I select, to let me know to put the clothes into the dryer.
6) Device electronics / control should be isolated to prevent the additional complication from increasing failure rate.
It's stupid, bad engineering that the more features a home appliance has, i.e. the more premium it is, the more consumers see failures. If the toaster can't get online, it better still make my toast when I press the button.