For example, Shakespeare wrote all of his works in near-perfect meter. That's partially what makes him great. Writing in meter is laborious, and not until the 19th century did poets truly leave it for less formulaic works. Take the following line. It's one of Shakespeare's famous lines. I'm going to capitalize the stressed syllables:
...a HORSE, a HORSE! my KINGdom FOR a HORSE!...
The problem with teenage poets is that they don't even acknowledge meter. Even a poet who doesn't confine his/her poems to meter should first understand and be capable of keeping the human ear pacified, otherwise your voice tends to end up like crap. That's partially why "emo poetry" is looked down upon - the authors don't know shit about meter. That, and they also don't invoke any emotions. It's just ranting.