Are Microwave Ovens really bad for our bodies?

Yes, don't ever get in one. Microwave energy is dangerous to your cellular structure. Period. In whatever form it is presented in your science, including transmission for communication, it's dangerous. There is no reason to throw away the science, instead, understand it and devise protection that is appropriate.
As to the microwave oven, you would be better advised to know what is happening to the food you ingest that has been cooked with it, rather than being afraid of the oven itself. Microwave energy removes much of the nutrition from anything cooked with it. It's not the same kind of heat you would have from a fire. Therefore our advice has always been to use these ovens sparingly and not as your prime source of heat for cooking.
My partner says popcorn is okay.