Probably because a lot of us have read or watched his work and know first hand that it was extremely high quality. It's not like you have to take people's word for it.
The Feynman Lectures on Physics was used as the textbook for Caltech's introductory physics course for nearly two decades, and it is still used in some universities. I learned physics from it and have met many Caltech alumni who used it as their textbook, all of whom felt they learned a great deal more than "intuition" from it. So I am guessing you've never actually tried to learn something from it if you feel that way.
