Well, I'm no expert, but it seems like it tastes worse because of the uneven heating/adding too much energy to one area and not another. So texture changes and certain ingredients change flavor based on how much or how little energy they receive.
As for popcorn, I'd argue the difference is also uneven heating leading to unpopped kernels/random burnt taste if you try to pop them all. But also the packaging required to pop them in the microwave (and what's put inside that package) changes the flavor.
A big part of cooking for me is the control of how my food cooks and what I put into it. I'd rather wait and have it how I want vs getting it now with a bunch of other factors I can't control.
Priority -1 - I'm showing up at your door.