User blog comment:Darknesslover5000/Is Ichigo going to lose his Hollow Powers?/@comment-1769234-20100704074511

This could mean that the Hollow within Ichigo is just a power that he must master before he can learn the final Getsuga Tensho. As stated by Hollow Ichigo both him and Zangetsu are the center body of his spirit energy.

Another theory is that when a Hollow Ichigo fought against Uliquorra it made the hollow ichigo stronger and it hurts Zangestu that he dependents and its power rather than his or Zangetsu.