I moved to a new apartment with all this stuff installed.
replyAt first I thought exactly that - just why.
When days started getting warm in the beginning of the summer I started investigating and thought that it might actually be a good idea - you could turn AC an hour before you come home to find cool room.
When summer hit I actually found out that you just leave AC on all the time and it just keeps temperature at 22C or so and there is really no need for it to be connected. You don't want to turn that off as it is more economical to keep the room cool than letting it to get hot and then trying to cool it fast. It barely even showed up on my electricity bill at the end.
So all in all - really not needed.
My connected thermostat used the weather to determine expected outdoor temperature and sun exposure to adjust timing of heating and cooling as well as presence or absence of cell phone “at home” to adjust temperature range for savings. It also used cell phone approaching home to go back to normal temperature ranges.
replyMy dumb thermostat also accounts for outdoor weather and sun exposure, simply by directly measuring the indoor air temperature which changes in response to those things. Dumb ones can also have schedule programming too. There's been plenty of times running errands when I approach home and then pass it up. Usually better to keep your temp constant than go through heating/cooling/big delta cycles generally speaking anyhow. One of those things where it feels like it makes sense but probably doesn't if you are coming back that day anyhow.
replyConnected A/C has been useful for me, because I also have a window fan and outdoor temperature sensors. So when target temp is below indoor temp but above outdoor temp, I turn off the A/C and turn on the venting fan. It's a lot more energy efficient.
replyNow, is it connected to the internet? Ha ha ha, no.