I think that depends on when in the process you crop. If you crop in post, then yeah, it throws off the balance. If you crop your head out of the frame as you take the picture, the composition is generally fine. In general, it interferes with my appreciation of what people are wearing. This is especially true of the pictures of people where is is like 70% head, 30% torso. It feels almost like it is about their face and not about what they are wearing.