(Addiction metaphor, time to go cold turkey etc.)

I'm about five seasons early here, but I really like stormwreath's take on the addiction metaphor: it's not so much that magic is like a drug, but that the Scoobies (without any sort of mentor at that point) treat it as if it were. They act as if they're in a PSA about not doing drugs, and if they just do what the people do in those it'll work out; they're wrong, the magic is just a symptom of something in Willow that's been unaddressed ever since... well, "I Robot You Jane", and so it blows up in their faces. I'm not sure that's the writers' intention (in fact I'm pretty sure it's not) but it makes that arc a lot better.