[dasyatidprime]

Most of the problem with browning is the physics: it requires temperatures well above boiling, but the default microwave absorber is water which will tend to saturate around boiling temp. But physical cookware design can be used to make it work: the article I linked prominently describes the use of a browning skillet with a tin oxide coating on the bottom that can safely absorb large amounts of microwave radiation and get hot enough to brown foods.

So partly due to that, I think if you wanted to do full robotic cookery with a microwave beyond the TV-dinner stage you'd still need control over the other objects rather than just switching the magnetron. Stirring for even heat distribution is another thing.

And then it's separately interesting how, in a really skew way, “deliver heat using RF energy” came back from a different angle with the rise of induction stoves!