Just as critical, even if the issuer guarantees you zero liability for fraud, is the fact that with a check card your money is gone first, then you fight to get it back.
With a credit card you just dispute the charge and don't pay. That's the most important reason I won't use a check card. If someone gets hold of my information, I don't want to be broke while I fight to get some faceless drone at a bank to give me my money back.