It should be noted that this baggy pants/shirt fashion trend for men is mostly a recent American trend. If you visit Europe and Latin America, men are wearing tighter clothes. I suspect the baggy look is an affect of our prudish country.
As a 40-something, I do remember a time when it was cool to wear tight jeans going out to the club to attrack women. I too am unclear when the shift to baggy changed (other the the hip-hop fashion trend).

I find it wierd seeing all those music videos with women in tight fashions and the guys in the most baggy clothes they could find. What's the attaction for the ladies. Guys work out a lot but then don't want to show it off. If you do, (especially wearing tight enough jeans that show your package) people think you're gay! I do belive in comfort but I do like to wear pants that women can look at me as a man with something to show. This isn't the same as having my dick laid out flat against my thigh like an exhibitionist!