My brother owns a tattoo studio and has a plethera of stories about his clientel and their sometimes wacky choices for a tattoo. That being said, it is a personal choice to get "inked" and for those who didn't do it on a whim have put a great deal of thought into the "what and why" of it all.
Tattoos are not a fad. It is a choice in life just like anything else I guess...You choose to get married and if that doesn't work out you get a divorce. You happen to fall on a tattooist and get a great big hulking ugly sort of a tattoo on your chest and it's just as hard to get rid of it as it is a nagging old woman. Most of us with tattoos really love them and could not be without as they become part of who we are.
Speaking directly on the matter of chest tattoos...I particularly don't like them on women. I like breasts too much to see them adorned with anything else but the skin God put on. I could care less what a dude does to his chest...It's the ladies who need not place an ounce of ink where God has seen fit to create a man's favorite place to motorboat!