]It's much less of a headache to pretend the word "wicca" was never mentioned in BtVS, ever. Otherwise, you'll have to listen to me rant about neo-paganism, eclecticism, and religion for like a page, just because.
OR we could go "maybe in this universe, wicca's not like that. Maybe in 95% of universes, wicca's not like that. But in Buffyverses, wicca is actually how it's seen in the show!" Changes in alternate time lines is always an usable excuse, because maybe wicca 'evolved' differently in a world filled with things that go bump in the night like vampires and demons.[/quote]
Congratulations, you just activated Lecture!Satori! This gets you the Word of Mod Achievment and 9 renegade points.
Wicca=/= Withcraft
The latter is a term that can be generally used to describe the practice of magic.
The former is a BDSM-ish fertility cult (Yes, fetility cult, i means what you think it does) started in the 1930's-50's (exact date is unclear to the secretive, paranoid founder) by a British civil servant with occult interests. It should be noted that some traditionalist Wiccan covens actively forbid homosexual members because many of their rites are explicitly heterosexual (and generally between married, or at least committed, couples), and thus Willow and Tara would not be Wiccans.
In fact, no TV portrayal of witches is "Wiccan". The closest they come is some being eclectic neo-pagan.