Well Ichigo is a hybrid whether he like it or not but aside from the whole 'my hollow side is taking over' schizophrenic problem, his hybrid condition is really pushing his develpoment rate along. Even Aizen's crew admits to knowing it. With such a big growth rate I wonder if Ichigo will hit his limit soon? If he does then he'll HAVE to learn Kidou if he wants to be an even better combatant. Ha ha, problem solved.