Microwaves are looked down upon because they do a lousy job cooking a great many things, especially meats, which is one of the things they were initially marketed for. Remember when they advertised that you could cook a turkey or a roast in much less time? For thick things they work incredibly poorly since they largely can't heat things much past the boiling point of water (water is a large portion of the molecules in food that microwaves can successfully heat) and they only penetrate the meat by a few inches. That means that it's possible to cook a steak, but cooking a roast means you'd have to rely on intra-food conduction to cook the center, and since that sort of conduction takes a long time during which you have to continue pushing heat into the food, the utility of using a microwave in the first place is lost.

At the same time, you cannot form any sort of browning on a steak due to the low temperatures involved, and that's, at best, unappealing, and, at worst, just tastes lousy. Also, since the microwaves do penetrate beyond the surface somewhat, you have a hard time getting the outside done while leaving the inside medium-rare.

Also, and I don't have much to back this up, my personal experience is that microwaves make meat rubbery.

But they're great for reheating, as you seldom want to reheat past 212F/100C anyway.

As to your points: You must like rubbery eggs. I've had microwaved scrambled eggs and they're terrible. Maybe you add a lot of milk or cream? I have no experience with kippers at all, but they're thin and require low temperature cooking, so I can see how that might work well. And, you're right; it's hardly difficult to boil some water on the stove, and the microwave might end up cooking the egg via the microwaves instead of from the conduction of the boiling water, which probably wouldn't work well.