It's a fair point.
I'm sure we could all think of a few teen characters at Marvel we'd LIKE to see. But in all seriousness this is the issue. There is no unique concept to get them on a book of their own. Between Young Avengers, Arena, Wolverine & the X-Men and maybe even arguably All-New X-Men younger characters are getting a pretty decent amount of page time.
Maybe not the original poster's FAVOURED characters, however.
Marvel dioes have this problem though. The original 5 X-Men, New Mutants, New Warriors, Generation X, New X-Men: Academy X, Avengers: The Initiative, Avengers Academy, Young Avengers, Runaways... There have been a fair number of teen character books over the years. But with the sliding timescale being what it IS it's often hard to know what to do WITH them once one incarnation ends and another begins.
Who's older than who? Where do they fit? When a writer promotes one of them to an A-Team does that mean they can ever go back to being a Youngster? It all gets very difficult to decide upon.