Vitalik Buterin provided a strong counter argument. But regardless of whether PoS has more gameable entropy or not, for sure PoW can distribute new coins (and redistribute existing wealth...a necessary requirement of all money since dawn of mankind) and PoS can not.

Why necessary to redistribute money (at slow rates of debasement)? Because otherwise the macroeconomic incentives to invest with risk to produce more instead of save in deflation are not balanced.