Well said, Pussyman. Some folks may laugh, but evolutionary biologists and people who study human behaviour say that the reason many men are obsessed with breasts is because of what breasts meant to them in their formative years. As weird as this sounds, to an infant, the breast means warmth, safety, nourishment and love. That's why little kids are often given pacifiers to suck on when they're upset. It's just a replacement for the breast. It's also why most people have to be doing SOMETHING with their mouths, even when they're adults (smoking, chewing gum/tobacco, chewing on the end of a pen). Let's face it, many men (and probably more women than will admit it) have a breast fetish. Female breasts are some of the most beautiful things on the planet, and that's why I take every opportunity I can to touch and see them. There's just something wonderful and comforting about playing with breasts.
It's also worth noting that in North America, of course, breasts scream "sex" in capital letters. Since many North Americans use missionary style, bare breasts have come to be virtually synonymous with sex. Rightly or wrongly, a woman going topless has become unconsciously representative of impending sex. In places like the Orient centuries ago (where doggie style was more common) the back of a woman's neck was as titillating to them as breasts are to many of us. This is because the back of a woman's neck is what a Korean or Japanese guy would see during sex, just like most of us see a soft pair of tits.