> (...) but all else being equal, exposed steel is better (...) No, it's way worse. The outermost concrete layer serves multiple purposes, including corrosion

> (...) but all else being equal, exposed steel is better (...) No, it's way worse. The outermost concrete layer serves multiple purposes, including corrosion protection and fire resistance. Exposed rebar can and will start corroding immediately if not covered or treated, and in turn it loses grip and resistance.