One of my favorite uses of the microwave is to reheat food. Since it works by heating up the water molecules, it doesn't seem to dry out the food. Also, you can heat it up right in your bowl/plate. And, since your plate/bowl can then go right in the dishwasher, it is one less plate/bowl to wash. And it is fast.
Heating leftovers up on the stove usually requires washing a pot and eating out of a different dish. Which, lets face it, is a pain.
While I don't know that microwaves are an unmitigated evil, I have been reading about how