If DPS is the only thing you're worried about, sure, but in practice and survival/turtle tanking, I've found that C&S is more valuable for its mana restoration than the mitigation-less 450-potency damage you get out of it. Then again, I main a PLD, so perhaps I just need more practice at mana management on DRK (I usually try to keep ~50% MP at all times in case of emergency).
*switches to PLD and pops Hallowed Ground to weather the incoming storm of "UR A BAD DRK"*