You guys have to understand that this is a Syth right of passage. You see, the master Syth is always testing his apprentice and this could have been a test to see if Anakin was indeed powerful or if Dooku was the rightful heir to the Syth legacy. Just how the Emperor did to Luke and Vader. The Syth Lords were always cruel to their students but this was to assure that the student was kept on their toes and to weed out week Syth.