Being able to do things like change it based on certain conditions, like switching it off if I open a window and not activating it if I'm away from the house over the time it would normally turn on. I can also remotely turn the heating up when I'm heading home, so the place is warm when I arrive.

In my case though I'm using Home Assistant on a local server and Tailscale for remote access, so nothing is connected to some company's online service and the actual devices are all offline only.