Nazi Germany's economic collapse had far less to do with being a command economy than it did with, y'know, fighting a massive war on two fronts...and eventually ground down.
Which actually stemmed from the same philosophical premises as the command economy of the Nazis--namely, Old Pre-Kahn Eugenics (the idea of "purifying" man and society through government action, regulation--and millitary might).
As for the command elements in our society: yes, they are good--to a point. Left completely unrestrained (with no laws punishing fraud, etc.), a free market would destroy itself. It would disolve into anarchy, which is not truly free.
A true free market does
allow for regulation, but there are limits to this, so as to prevent unneccessary incursion into the market, which hamper
production, rather than encourage it.