Aside from the psychological stuff, such an extreme departure from horizontal foreshortens the height of the figure. In this shot, the model's body is "squished" to a very short appearance. Consequently, the eye tends to notice the model's hips. The same effect will occur if shooting upwards in a steep angle.
Now all these theoretical "problems" are sometimes done on purpose, providing the photographer knows the effect and desires it, but as you are "just starting out", you are just now learning about it.