I not only think they DO, but I also think some change is essential. A story:
My best friend in college (the first time!) and I were a lot alike. Very bitter and angry, lots of drama and angst, depression, very negative outlooks, the whole nine yards. Like I said, we were best friends. Drank beer and bitched together, snarked about the same people, an enemy of one became an enemy of both, etc.
However, I dropped out, moved and started working/going to school/working/basically being on my own, while my friend continued in school, stayed living with his parents, went to grad school, etc. It’s been 3 years and he hasn’t changed a bit.
I have, though. I haven’t quit HATING my parents, I just realized everyone hates their parents and cut the one that really pissed me off out of my life and keep the other at arm’s reach. It’s amazing what 800 miles and email-only communication will do to make a person less irritating. I’ve gotten rid of my darker outlook, not so bitter anymore, not angsty at all, etc.
And, frankly, now he’s kind of obnoxious to talk to. I think hating your parents and being miserable about it is fine in your late teens and even into your 20s some, but at 23, you need to be able to tell your parents to fuck off if they bother you that much. After my time in the working world, I don’t really care about the inter-class drama that comes from going to a pretty small cool, since I’m very much a “Put in my 8 hours and go home”-er. And I enjoyed wallowing in angst for a while, but there’s just a time when you have to let it go. Whining about the terribleness of the world when you’re 19 and really can’t do much about it is one, but whining about it when you’re a college-educated 23 that could do quite a few things about it is another. I feel kinda bad talking this way about him, but at the same time…damn he’s obnoxious. Which isn’t to say I wasn’t/am not.
I think growth and change is often an essential part of a healthy emotional life, I guess.