Well I haven't see any more that you, but I think what they are doing is using magic as a metaphor for drugs, in so far as drugs are something that many people dally in, and can be arguably be used for a substantial purpose - for example the great romantic poets such as Coleridge often wrote under the influence of Opium. It is something that can control the user, instead of the user controlling it, and I think this is what they'[re showing - the habitual use whereby not a day goes by where you could exist without using it. It would be a shame to see Willow give up using magic altogether though, she has used it to such benefit in the past.