It's always struck me as odd that just about every microwave out there will put a couple of thermal cut offs in there but none of them have any kind of microwave intensity sensor to actually detect when the cavity is empty or presenting too low of a load. Even the naive approach of just adding a weak antenna and attenuating the crap out of it would seem to be cheap enough in added parts at least for "luxury" brands and it would not only protect the microwave from damage but also allow fine power level control based on actual intensity instead of just total load.
Yeah, I pop popcorn all the time.
After enough iterations, I've learned that 2 minutes and 22 seconds is the right amount of time. A longer time risks burning, and a shorter time won't pop as many kernels.
With a knob, I don't think I'd be able to dial in 2:22. So I'd have to stand there and monitor it the whole time instead of being able to walk away. And microwaves are supposed to be convenient.
The one I have now, a higher end model with plenty of features and auto-stuff. But it is actually simpler when used as a basic microwave.
It has two big buttons: start and stop. If you press start, it sets the timer for 30 seconds and runs at max power. If you press the button when the microwave is running, it adds 30 seconds.
If you want more precise timing, you can also preset the time using + and - buttons and set the power with the "power" button. Then press start.
It also has a nice safety feature. The microwave will refuse to turn on if you didn't open the door recently. This is to limit the risk of running it empty, which can damage it. From my experience, it is an actually useful feature and not an annoyance.
So, 3 improvements over the "two dials" interface: easier for the most common case (30 second start), more precise timer when you need it, and an added safety feature.