Hugs are not as personal as a handshake.
Excellent hugging intimacy is characterized by face-to-face, eye-to-eye contact between the parties. Most hugs fall short of this level of affection for tall people.
As a result of the fact that the other participant will only barely reach chest height for many tall persons in 99 percent of hugs, this is a common problem. When hugging someone, squatting and kneeling can be beneficial, but it reduces the amount of time the hug can be comfortably held.