Within the "traditional foods movement", microwaves are often eschewed. I have come down on this issue in a different place than most and am going to discuss in this post why I do not think microwaves are evil.
microwaves & language issues
Much of the anti-microwave sentiment expressed is badly-worded language designed to make people without much of a science background feel nervous.
For example, it is said that microwaves heat food by using RADIANT ENERGY. But all light is radiant energy, from the sunlight allowing your skin to make vitamin D to the most basic cooking of all, over a campfire like our ancestors did all their cooking. The entire light spectrum is radiant energy! However, by saying it as if it's a scary word, there is the hope you will vaguely misunderstand and think that microwave ovens are radioactive, which is not the case.
Another example is the worry that microwaves make the molecules in your food move faster. Heat is a measurement of how fast molecules are moving in the first place so this is true of all hot foods. If you want molecules moving slowly, eat cold food.
It is said that microwaves change the molecular structure of food. Yes, they do. It's called "cooking" and if you don't want the molecular makeup of food changed, you need to eat it raw.
Microwaves destroy vitamins. This is true, and is also true of stove-top cooking, oven cooking, crockpots, dehydrators, canning and even freezing food. Sprouting and fermenting are about the only things we can do to food that increases nutrient levels; generally, food has the highest level of vitamins when fresh.
There is the worry over proteins being denatured by microwaves, though all cooking methods denature protein. Denature simply means the protein is unfolded. This is the first step of digestion, even when you eat raw protein, the hydrochloric acid in your stomach denatures that protein.
Microwaves cause "ionization", another scary-sounding word. However, it is the process that occurs when salt dissolves in water, so not exactly something to get up in arms about. Though chlorine is a poisonous gas, when ionized, it forms the chloride ion, a necessary nutrient. So ionization is not bad, and RIGHT NOW your blood is full of ions, all the minerals we need are used in ionized forms, even when chelated, they are ionic.
Sometimes I read rants against microwaves using this sort of language and assume the writer is ignorant. But sometimes, I see articles written with this language by folks with real science backgrounds and it bugs me they're apparently just engaging in fear-mongering.
microwaves & research
There is some genuine research out there. There is the fact that baby formula when nuked, produces nasty compounds. Given that there is NO way to heat vegetable oils without producing rancidity, this is true of heating it at all. In fact, it will happen just from leaving baby formula sitting on a shelf at room temperature over time; polyunsaturated fats are simply not stable and go rancid easily. This is one of many reasons that babies ought to be fed human milk rather than baby formula.
And there is the case of the nurse who tried to thaw a bag of frozen human blood in a microwave. Of course, heating blood means the cells burst open, rendering the blood useless, but this would've been the case if she'd heated it on a stove-top too. Blood isn't supposed to be heated much beyond 100 degrees Fahrenheit.
In Nourishing Traditions, Fallon & Enig reference research done by Hertel and Blanc. I don't know where they got this. I can find lots of web pages referring to it, but cannot find the research itself anywhere.
So all I can conclude is... nothing. Nada, zip. If I can't read the research and see how it was done, I can't tell if it's something that would persuade me or a bunch of hokum. I DO get that Fallon & Enig are more authorities in nutrition than I am, so it's no skin off my nose if you believe them. Just... I don't believe research I haven't read myself.
There is a time when you shouldn't use a microwave, and that is when the container you are nuking in is plastic. Plastic adds nasty compounds to your food if you heat in it, so it's best not to. You want to reheat in glass or on a ceramic plate or such. This is true even if we're talking a toaster oven instead of a microwave. The dangers of plastic increase when you heat it, even if it is so-called microwave-safe plastic.
microwave conclusion
For me, a microwave is indispensable to the way I cook, though I rarely use one for actual cooking at all. I like the Malliard reaction, that yumminess that occurs when browning meats or vegetables, and you just can't get that in a microwave. While cooking, the only task I nuke for regularly is melting coconut oil.
I use my microwave mostly for reheating. Since I cook in big batches, almost every meal I actually eat is "leftovers", whether straight from the fridge, a home-canned meal, or a meal I've previously frozen.
You can tell me that it's just as easy to reheat in a toaster oven or on the stove-top, but for me, it just isn't. For example, I can cook eggs in a muffin tin with some chopped veggies and meat and eat them for breakfast all week. To reheat in a toaster oven takes just as long as cooking them in the first place.
Even in those cases when the reheating is just as easy, there are more dishes generated using non-microwave methods of reheating food, whereas I can nuke in the plate or bowl I am going to eat from. When I didn't have a microwave for a few months (years ago, before I was disabled), I found it took much more time to reheat food, but the time was in cleanup, not cooking. That's why I bought a new microwave.
Though the cleanup might seem minimal time, when hubby did the cooking when my fatigue was really bad right after the surgery and prior to me getting a home health aid (HHA), I ate lunch meat sandwiches, yogurt and berries, and cottage cheese... for many months. I mean, that was almost my entire diet. Once a week, he'd get ambitious and fix burgers or pasta or eggs. The man does not cook.
I have only 12 hours per week of HHA assistance. We must get 21 meals prepared and cleaned up out of that, for both hubby and me. Plus we must have time leftover for assistance with showering and dressing and light housework like cleaning the floors and bathroom.
We eat cooked beans, pastured meats, gobs of broth, we eat pretty much entirely home-cooked, real foods. But most of the meals are nuked... without a microwave, I could not eat home-cooked meals due to my disability.
If I were convinced it was really bad to nuke, well, I guess I would switch to more raw food – back to lots of yogurt and cottage cheese. But... I really haven't ever seen any evidence that it's bad.
I do find it strange that so many traditional food folks, even ones who I know have a science background, are opposed to microwaves. If there is a REAL reason for it, I'd like to know.
rationale for microwave usage
For me, there have been many days where I was only able to eat at all because I had a microwave to reheat food in. Yes, I know you can reheat in a saucepan, in an oven or a toaster oven, but some days, that would seriously be too much for me. It makes too many dishes to do and I can't always stand and stir over a saucepan. Some days, eating at ALL occurred because I had a microwave.
Microwaves are not particularly traditional, but neither are electric or gas stoves. If you don't insist on doing all your cooking over a fire, I don't see why you can't use a microwave.
IMO, the whole point of a microwave is not to cook, I rarely cook in it. The point is that I can cook in advance! I can cook when I feel like it, and then eat real, home-cooked meals when I'm not up to it by quickly nuking.
If you're opposed to microwaves, well OK, I won't make you use one. ;) But I just want to give you permission to use a microwave if it makes your life easier. Don't nuke stuff in plastic containers, but otherwise you can nuke cause Jackie said it's OK. ;)