Hmm, I guess I don't really think it's repetitive? I think it's delving into Dean's psychology in a way the show hasn't done before.

This being SPN I doubt any form of "cure" is in the cards, but I would hope the show will take steps to ameliorate the path of complete misanthropy Dean is falling into. Yes SPN does take a dark perspective but it's also a show about brotherly love saving the world. At this point, even Dean re-gaining some ability to hope for a better future would be great progress for the character.