Why men like boobs? It is biologically designed and personal preference.
A pair of boobs is just a sexual appeal to men. Similarly, a thin waist indicates to men that a particular woman is not pregnant and she is ready for carrying offsprings. Either a big pair boobs or a thin waist is an area that men look for sign of youthfulness, one of the most important criteria when men is looking for a mate.
Also, when i say personal preference, not all men like big boobs, some like small ones. some men like looking at women's neck, hair, legs. it is all depends on the individuals.
Fans of 趙 碩 之 like boobs. Some fans of GiGi Leung, for example, like her pretty face.