None of this stuff is new, Chuck.
I'm sure parents had the same lament back in the 60s, when all major department stores began carrying mini- and micro-skirts for eight-year-olds.
I grew up in the 80s, and if anything I think teens were far more blatantly "sexualized" back then.
Hell, there was a whole genre of movies entirely about teenagers screwing.
The Blue Lagoon was probably the most popular one, but there were a bunch of knock-offs, and also a bunch of movies that played mainly on late night cable that were entirely about, say, high schoolers getting laid. Or else high schoolers trying unsuccessfully to get laid.
The attitude toward abortion was much more laid-back. Look at the casual, blase treatment of abortion in 1982's classic "Fast Times at Ridgemont High". You would not see abortion treated so lightly in a movie today. Popular film-makers today tend to avoid the issue entirely, since attempting to deal with it, from any perspective, is akin to poking a hornet's nest with a stick.
Back in the 80s, all of the most popular teen actresses did nude scenes, sometimes even sex scenes. Phoebe Cates, Brooke Shields, Jennifer Jason Leigh, ALL of them. And yes, they did them while they were still minors.
Today, we've got people going ballistic because a 15 or 16-year-old Miley Cyrus appears on the cover of a mainstream magazine draped in fabric which exposes her bare shoulders. Oh yeah, she's also wearing lipstick. The horror!
So, let's see... in the 80s we had tweens and teens wearing tube tops, slop-buckets full of makeup, and Guess jeans so tight they had to zip themselves into them using a coathanger (remember that?).
To me, teens seem more innocent today than they did 20 years ago; more childish, more prudish.
Kids were more sophisticated 20 years ago, better at impersonating adults (or at least, more interested in doing so).
In the 80s (and the 70s, and the 60s...) kids smoked, drank, and did a lot of drugs. And had a lot of casual sex (or at least attempted to). They partied.
True, some kids still do these things today, but it seems like those are the "bad kids". The rebels and outcasts.
Back in my day, these behaviors were pretty normative. It wasn't only the bad kids that did them. It was the mainstream kids, too.
Many, many kids in the 1980s were latch-key kids, children of divorced single working parents, raising themselves and in many cases their younger siblings as well, without much adult supervision.
Today it's just not acceptable for an eleven-year-old to come home to an empty house after school and babysit his two younger brothers until mom gets home. This situation is frowned upon.
But back in the 80s, that was just the way things were done. It wasn't considered strange or inappropriate or dangerous or illegal.
Kids had to be more mature, more independent. They had to grow up faster back then.
Today, I think maybe we shelter them too much.