Willow being a lesbian makes even less sense with rewatch....
She showed strong interest in numerous guys until the fourth season. There is not the slightest hint or indication that she is a lesbian or even bi until the third season with Vampire Willow. But even that is absurd. Because Vampire Willow was with Vampire Xander when we had seen her before. The show literally made them both gay in one episode. Even after that, she was with Oz and actually lost her virginity after the "Willow is gay" episode.
You don't just suddenly turn gay. Making her bisexual would have made much more sense, but they had her become a full lesbian out of nowhere that isn't attracted to men, even under spells.