I haven't used checks in my life and all but what will happen if someone steals your checkbook and writes himself some checks? Can you call the bank and have your money back?
If the Checkbook is stolen and whoever is holding it writes himself a check, he can't encash it himself since checks undergo signature verification. Holder of that check may pay someone that stolen check but who ever is the holder of that check and tries to deposit to a Bank account, issuing bank of the check will not honor the check because of the signature. More problem if the owner reported the checkbook as stolen.
I would say Checks are good only in real life transaction but not through online.