What is happening with Google? Its strange that all their bets are resulting in these kind of childish situations. I understand unhappy employees leaking stuff but coming from the upper management like this is not good at all.
Personally, I'm just not seeing it. The idea of a centralized or master system is old fashioned. People will just buy automation as they need it. So I'll have an app on my phone for my Ring doorbell, another for my garage door, another for my security system, another for my lighting, etc. Google is betting that people won't want this and want an Apple-like experience of just having one vendor perform all their tasks, but people without SV salaries aren't going to casually drop Nest-like prices (total cost of the system with multiple smoke detectors is in the four digits) all at once and they might resent a high level of vendor lock-in. They'll just pick up random automation pieces at home depot for $99 each now and again and just install a new app as needed. Its not a terrible inconvenience and so what if my doorbell can't talk to my thermostat.
Central management is key. Though I suspect most people would be better off using a central device many of them already have at home (a PC) than buying a custom piece of hardware to be the center of their home network.
Basing everything around your phone isn't a good solution, because it leads to having a half dozen accounts with a half dozen apps that you need to set up on a half dozen devices if you have a family...
But this is all a debate independent of Google's troubles. Between Android@Home and OnHub and Nest, Google's been trying to nail down IoT since before IoT was an expression people used. No sign they're going to get the hang of it any time soon.
I mostly agree with your overall point though. I'm just not sure what an automated home would really do that I should care about.
Your doorbell and thermostat have little to do with each other, but having your camera or your smoke detector as mention sensors for your thermostat is pretty useful. The smoke detectors especially, since they tend to be in the bedrooms, which is the place where you'll stay 8 hours a day without walking in front of your thermostat so that it knows you are home.
It doesn't work, but he's obsessed with velocity, so he keeps doing it.