They said the feature can help detect something abnormal (they gave the example of leaving a door or window open). If my heater suddenly requires 2x the effort to heat my home vs. the day prior, that’s a big win for me to know, and a big environmental win for Nest’s entire fleet to be checking for.
Agreed. It's not something that would be a huge deciding factor for me but it's a nice to have. I'm already getting the Nest report of my usage so this is more useful information.