Ellen wasn't cancelled because she came out, it was cancelled a few months later IIRC because ABC got sick of her being "too gay." But you're dead right about "gay as we wanna be" in 2001 not being very gay at all--wasn't this before Queer Eye For The Straight Guy? (Hey, since you mentioned Buffy, that show shied away from its gay character a bit too.)
DVD sets of the entire series of Roseanne go for like $10 around here. I have sometimes considered purchasing one just to rewatch the whole mess and see if I feel as ugly towards it as I used to. But I'll probably rewatch Mad Men first.