Getting an SMS if one of my doors opened during the day might be nice.
Drop in on light switches would be huge... But how do you manage drop in? If the consumer has to actually replace the switch with a "smart" switch, that's DOA (requires wiring, messing with the breaker box, etc).
Replacing a switch is one way, a pass through on the socket is another--you plug the smart device into the socket and your actual stuff into the smart device. That won't hit all devices (not everything is plugged into a socket), but would be a good way to get the more casual user involved.
If I got an SMS that my front door was opened in the middle of the day, I'd call my wife to see if she went home early. If she didn't, I'd call my neighbors and/or the cops.
My point on light switches is that (unlike outlets, which could just have a pass-through unit) they require someone actually un-attach and re-attach wires, which many/most home owners aren't super comfortable with. Even if they are, it's a meaningful time investment in comparison.
Drop in on light switches would be huge... But how do you manage drop in? If the consumer has to actually replace the switch with a "smart" switch, that's DOA (requires wiring, messing with the breaker box, etc).