If one think the "Hollywood teen" is the norm, then sure, but reality is far far far from that. Then again, I think most of us here knows that all too well. I mean, why did we become so obsessed about books, cartoons, anime, consoles and games etc in the first place? ;)

Luckily the gaming industry went the other way to make money on something a bit more mature and less stupid story/drama.

Adding Monkey Island. And, just to add a game to the list that is relatively new (which I assume OP actually meant); Horizon Zero Dawn. There aren't many games with teenagers and their infinite "struggle" today, thankfully.

There you have your simple answer. If a game isn't focused on teenagers like Life Is Strange*, and the game is not a 2D point-and-click adventure game with a couple of individually drawn characters, like most of Breja's examples, teenagers would mean one costly extra model without any other use than making the game a little more immersive for the few players who actually miss them. Usually the children - if there even are some - are stand-ins for people having kids, because they are more easily distinguishable from adults and potentially cuter, I'd say.

(* Well, actually, IIRC, the characters are supposed to be in college and of age already, they just act and talk like high school students. Or how the French writers imagined teenagers in the US to talk, that is. ;D)

There's a rather simple explanation for this.

Children can be quite funny and adorable.

Adults are useful and productive.

Elderly people are wise, and sometimes adorable, even when they shit in their pants.

Teenagers, however... they are just entitled whiny brats. Thinking they are adults when they are just undeveloped shit who know nothing and can do nothing.

So, no one wants to see teenagers in games. Not even teenagers themselves, even they are tired of themselves.

Ahem, there is a very glaring omission here: Rockstar's Bully!

I'd definitely like to see more games like it, though not necessarily the teenager part - more the 'small town with small problems' setting. School bullies, evil local real estate developers etc.