You don't get much of a worker for $15.00 an hour. You get an employee who will flee at the first opportunity. If your factory operation puts cotton wads in Aspirin bottles, that may be good enough for you but those jobs have all gone to low wage Asian places, anyway. What is left for us in the Western World has a much higher custom element in it and more highly engineered products (our local Ford plant produces the most complex builds in the Ford lineup for export all over the world). You don't get much of a knowledge worker for peanuts. You get a coffee pourer at Timmy's. That kind of Service Sector employment generates relatively little wealth.
Keeping people down shrinks the economy.