That's my take and/or fanwank as well. Again we're getting ahead of ourselves, but.... Even the memory spells Willow can write off as having good intentions. It's very hard for her to find anything positive to say about her behaviour in "Smashed" and then "Wrecked." So then she really seizes on "it's the magic's fault!" so that she can still be good Willow, and not have to confront the moral rot that's set in. But she also cuts off a piece of herself in the process for the next half-season, and when she loses Tara the explosion is even huger. It's complicated, because Rack really does have druggy magic. But it makes sense for Willow to be drawn to that too, though it's not her big problem.

I'll add a point from Arbitrar of Quality (have you read those discussions? anyway) which is that Willow gives up on magic exactly when she encounters some magic that makes her lose her sense of control.

Who knows what was intended (my guess is that Wrecked et al. was really just a patch on the arc, not necessarily to make Willow look better, but to delay Dark Willow until the end of the season through any means necessary) but it does have some nifty resonances.