If we want to optimize economic growth with the most powerful force in the universe, compound interest, shouldn't we pay people the market rate which is usually some combination of the scarcity of labor and the economic value of that labor?

If this rate is too low, then that is what the welfare system is for. Forcing employers to pay a "living wage" for jobs that don't generate a "living wage's" economic value simply retards the economy and robs our children of a wealthier future.