I'm a bit inbetween. I kind of like teens how they are and I'm glad they are not limited by height like older sim games. But in contrary to your experience, how old or young a teen sim looks varies greatly. I've had some look way over 18 and I'm like huh? Where's the teen?? and some that look younger.(pretty realistic though)
Teens are my favorite lifestage though so one thing I have learned to master is the art of making them look various ages. I learned that you can't simply age them up and expect them to look different. They will look the same at every lifestage apart from a child of course. So I usually spend time in CAS tweaking their features to look their age according to what I want.
Granted I do use height slider and cc so I can't comment on vanilla teens.
I understand how some people feel about the "gap" being too big from a kid to an 18 year old looking teen. And it's just more fun and realistic to have sims of all ages in my game.
So I have successfully made teens that look more pre teenish. Then when I want them to be an older teen I tweak some things again. And once they age to a young adult they have to be tweaked again if I want them to look older. Else they still look like that same teen in my eyes?
Of course looks and ages are all subjective and different for each individual person IRL but we're talking a game here. Anything they add to make teens more distinctive is welcome to me ?
