I can't help but feel that you may be reading more into it than the show intended.
I think if they meant to put across life lessons, as it were, they would have done a better job of it. Often any kind of serious social/emotional issue (like in your examples) that were brought to light were simply to add flavour and almost never had any real resolution beyond a bandaid 'now lets get on with the more important thing - stopping evil! fix.
This isn't a bad thing, I think, unless you see BtVS as a show aimed at giving these lessons, and failing. I don't. To me it was a 7pm-slot entertainment with sprinkles of relevant issues and not much else. (Those daytime soaps, on the other hand...)
Although I do agree, the bit with Willow and her magic addiction was well done simply because it was taken so slowly. Of course, unless the core characters suffered the problems of abusive boyfriend/suicide/etc then those issues raised in other episodes have no choice but to be rushed and somewhat pat.