Well apparently Hartnell wouldn't return Moffat's calls...
That reminds me. Moffat mentioned if a Classic Doctor was to be brought back, Hartnell would be the one that should be. Hartnell's Doctor was pretty gruff at the start (Taking off in the TARDIS with Ian and Barbara aboard knowing full well he may never be able to return them to their time; almost cracking the caveman's skull...), until his companions mellowed him. All the other Doctors have taken after Troughton, to some degree, yet HurtDoctor did something horrifying and shameful. Amy and River have both warned The Doctor not to travel alone.
Maybe HurtDoctor is what Hartnell could've/would've become without the Companions mellowing him?