Anything where electrical on/off is helpful
- old style microwaves you twist a time. You can then leave home leaving your dinner slowly defrosting in the microwave and then when a given time from then enable power.
electric heaters. Turn on before getting out of the duvet or before you get home
kettles to turn on boil 10 mins before your alarm.
lights. Probably the single most common use case. Turn them on/off based on your rules. Like you program to come at common dark times or that far-distant bedroom lamp without having to walk to it.
any kind of time-based electrical cost avoidance. Some utilities charge less at night, so turn power on at night. Clothes driers.
In my home, I'm struggling at a maximum to think of 3 or 4 uses. I bought 1. Works!
Where I hit an imagination limit is that items I would like to better control I need the devices smarter. Take say a gas cooker. Here in California I would be very dumb to have everything electric as an electric outage stops heating and cooking so I deliberately diversify gas/electric. A smart gas cooker I could remotely turn on would be useful (not Anker). At the moment someone rings home and says put the cooker on.
If the cost came down to $1-$5 per port then I can see just using it everywhere, there are fringe corner issues like that lamp or that heater I could usefully "smarten" but at $25/port I'm thinking 1 or 2 at most. I looked in every corner of my home I got stumped at a total of 4 smart plugs. I'd happily take 1 or 2 more for free.
We all survived without these gadgets before.