I think it makes a difference whether you regard the label as prescriptive or descriptive.
I think many people who embrace the label -- perhaps most -- get an idea in their heads of what being a Witch means, decide they like that, and take the label for their own.
There comes a point in one's experience, however, which could be called a crescendo or a crisis, where being a Witch stops being about conforming to one's vision of what a Witch is and starts being about giving voice to something inside oneself for which one may have no name. Nonetheless, it is more real than anything you have a name for.
I suspect many people never reach this point. Perhaps that's why so much of what is called Witchcraft today remains superficial, hollow, and temporary. For those who do, it is either the threshold of a new awareness or the end of a journey.
I have long believed that the contemporary understanding of Witchcraft is corrupt, that most people don't grasp its true meaning. Of course, saying this publicly is enough to have whatever else I say dismissed out-of-hand; people don't like their beliefs challenged, and ad hominem seems to be the preferred defensive response. But the distinction is implicit in Starhawk's distinction between "power over" and "power within." I do not claim to speak for her, or to share her understanding of these terms; but the meaning I have found in them has been life-changing.
Here's an example: Most people think Witchcraft is about control, manipulation, manifestation in accordance with the will. But this is the essence of "power over." "Power within," on the other hand, sees interaction with the world as a dance in which one partner or the other may lead, but in which both partners are willing. Casting a spell ceases to be about squeezing a result out of one's components and becomes instead an invitation to cooperate to achieve a desired result. It's not about compelling the Elements, but asking them to dance.
There is a spirit here that is not limited to Witchcraft -- or, perhaps, it is simply that the essence of Witchcraft is not limited to Witchcraft, and "Witchcraft" is just one way of expressing it. When someone decides to dam a river to build a hydroelectric plant, in what spirit does he do this? Is he thinking, "This river and its environs are mine to do with as I please," or is he instead asking the river and its environs to cooperate with him in this effort? The latter is the spirit of true Witchcraft; the former is a corrupt.
This is my view. If we do not always proceed with cooperation, let it be because we have not yet learned how to ask for it or receive it; and let it be with humility, as the Amerind regards the deer he kills for food. Let it not be because we regard Creation as our plaything to do with as we please. That's not Witchcraft, to my mind. That's an abomination.