(on "Clumsy") I'm actually glad someone remembers that early-90s stuff.

Aww, nostalgia.
On the topic of angst, I think it's natural, or at least very common, for people to become less and less myopic as they grow up. When we're little we only know about the world we see - home, school, the neighborhoods we live in. As you become exposed to more people and situations and places, you begin to get a somewhat better idea of the scope of the world, a sense of perspective. A skinned knee to a 4-year-old is like the end of the world. We very slowly grow away from that.
(Also, I think that people who have been through actual, real hardship tend to seem more mature, at least to me. They are forced to put things in perspective when some of us have not had to yet.)
By the time we hit high school we have somewhat of an idea of what is really important and what is not, but most of us (myself included) still tend to see ourselves as the center of the known universe. Worse yet, I think our culture fetishizes the high-school years, and preaches that THIS THE MOST IMPORTANT PART OF YOUR LIFE. You MUST pick your career/college NOW or YOUR LIFE WILL BE DESTROYED. You MUST go to the prom and have a PERFECT time and have a PERFECT lay afterward or YOU WILL NEVER DATE AGAIN. This is your LAST CHANCE TO HAVE FUN, EVER, so BE HAPPY, DAMMIT. The-sky-is-falling hysteria is the order of the day, possibly because educational administrators want to think that their jobs are critically important, or partly from parents trying to live vicariously through their kids (that's another rant entirely).
So, since most people don't have the perspective to see through this line of BS, they tend to accept that these people know what they're talking about. And accept the idea that life ends either when you graduate, or when you graduate college. To this day I find it really hard to shake the concept that life ends at thirty.
Nowadays, add into this a popular music movement centered on navel-gazing, self-pitying screaming, in which one girlfriend dumping you means Your Life Is A Pit Of Neverending Hate, and you have a perfect recipe for a lot of people feeling sorry for themselves as loud as they possibly can.
I figure everyone will get past it sooner or later. I didn't have nu-metal, but I was most definitely a self-pitying whiny teen-angst cliche in my day (They're just trying to keep me down!!!), and I got over it after I went to college.
Which is why none of it should be taken seriously.