I totally agree. Angst does tend to wallow in it's own depressing-ness, and for me I think there's kind of an emotional payoff from it. I don't really know how to put it any better than that. I think a lot of people get pleasure from reading angst because, as you said, it allows them to experience emotions and situations they wouldn't otherwise experience. It does tend to have an over-the-top element, but I also notice that angst stories usually seem to have a happier ending than depressing stories. Like, 'the main character suffers and suffers and suffers, and then everything turns out okay' versus 'the main character suffers and suffers and suffers and then dies miserably'. Big difference there.

Angst is gratuitous on some level, I think, and it is emotional porn in a way. You are right that angst usually provides a safer setting for dealing with painful things and often seems to distance the reader from the more agonizing aspects, or at least softens the blow somewhat. The reader can choose to empathize with the suffering character as much or as little as they like, and can usually 'pull back' a little bit if they feel they are getting too emotionally involved. I find that depressing stories don't really do this. You get the full brunt of painful experiences and emotions, without the emotional gratification or empathetic pleasure. I usually classify a story as depressing if it is relentlessly bleak, ends on a very grim note, and feels personal rather than empathetic.