Yes. Cav is a great sprinter, winning GTs is another level.
Than your PoV is strictly subjective (and wrong imo). You act like everyone ncan be a top sprinter at will, which is obviously not the case. Cavendish can't climb, but Pereiro/Cobo can't win tens of stages in a GT. And the sheer fact that teams (and personal sponsors) were willing to pay him couple of millions shows that his skill is highly rated and perhaps more important for the sponsors than a potential GT winner.