I expect two dials on any microwave I use: Time, Power. Maybe a control to set the time, if it has a clock.
I don't disagree with your general point about tools being able to be reprogrammed, though. One of the reasons I loved Autocad as a tool is the Lisp interpreter that allows you to script and extend it. I think that's a perfect example of a professional, mainstream tool with a good API that non-programmers find useful (if only to run scripts they find).
http://www.samsung.com/se/consumer/appliances-kitchen/microw...
But when you look at the Samsung US range of microwaves:
http://www.samsung.com/us/appliances/microwaves/all-products
...it becomes clear that (Samsung US belives) simplicity doesn't sell as well there...