BlastOff has nailed it. Back then, the waist of your pants was worn way up, almost at the navel. This meant that your entire package went down one leg or the other.

Now, people wear their pants much lower, on the hips -- but the rise (the distance between the waistband and where the legs start) of men's pants has remained the same. This means that there is a lot more vertical room in there, and you're not going to need to hang down one leg or the other unless you're truly gigantic.

Only recently have we started seeing low-rise pants, which allow people to wear pants on the hips, but still have the crotch come up to where it used to. And I've only seen this in jeans, never in anything more formal.

I tried a pair of very low-rise jeans on at the Gap. Good God, that was blatant. "Hello, I'm <Spork>, and this is my penis. We're pleased to meet you."