It's somehow related to our Puritan culture roots.
Anything relating to sex is BAD.

To compliment a woman on her breasts means you have seen them. If you have seen them enough to formulate a compliment, you must have paid some kind of attention to them. If you paid that much attention to them, you must have been staring at them. If you were staring at them, you must be some kind of pervert pig. And being a pig is bad.

That's usually how the logic goes. Sad but true, since female breasts are beautiful, and I'm still not sure why women are averse to hearing it.

I don't see how it's any different than complimenting a guy on his muscles or his chest, which is acceptable. Or even complimenting a girl on her hair, which is also acceptable.