You'd have to be a really careless reader to conclude that Andea Dworkin believed that all heterosexual sex is rape.
What is true, is that men's rights activists and other anti-feminists promote that lie, and many others about a few white feminists, to try and discredit all of feminism. The on-going atrocity of rape by men against women and girls disproportionately, along with domestic violence, sexual harassment, and men procuring, trafficking, and sexually enslaving women means that feminism is needed now more than ever. There are currently 30 million sex slaves, almost all are girls and women, almost all the slavers, pimps, and procurers are men.
Andrea Dworkin didn't promote the sexual exploitation and violation of children by adults, including by parents. There is a gross misunderstanding of a portion of her first feminist book, Woman Hating, which she later explained she'd been too influenced by Freud. But even in that first book, she wasn't talking about "incest" as we now understand it. She wasn't advocating any kind of abuse. Her work is quite clearly anti-abuse. (That was published in 1974, don't forget.) And the fact that she was speaking about erotic-spiritual energy, not sexual predation, ought to be clear to anyone reading her work. She has written and spoken out against all forms of child sexual abuse by adults.
Dworkin's work from the early 1980s onward contained frequent condemnations of incest and pedophilia as one of the chief forms of violence against women, arguing once that "Incest is terrifically important in understanding the condition of women. It is a crime committed against someone, a crime from which many victims never recover." In the early 1980s she had a public row with her former friend Allen Ginsberg over his support for child pornography and pedophilia, in which Ginsberg said "The right wants to put me in jail," and Dworkin responded "Yes, they're very sentimental; I'd kill you." When Hustler published in 1985 the claim that Dworkin advocated incest, Dworkin sued them for defamatory libel; the court dismissed Dworkin's complaint on the grounds that regardless of whether Hustler's interpretations of her reflections on incest were valid, even a faulty interpretation of a work placed into the "marketplace of ideas" could not amount to defamation in the legal sense.
Andrea Dworkin was valued because of her brilliant mind and great writing, capable of putting complex patriarchal realities into clear language. We need more women like her in the world, given how much abuse of women and girls by men there is. If you're not familiar with her actual writings, I recommend starting with Letters From A War Zone.
She should be regarded as a great human rights activist and humanitarian. Few people have been willing to speak out so clearly against men's violence against women and girls.
http://www.snopes.com/quotes/mackinnon.asp (see the portion on Dworkin)
More proof she never said all heterosexual sex is rape:
Here is a very good website with many more statistics and information on prostitution in the U.S.:
90% of women who are under the control of pimps if in prostitution. And most are abused in various ways by the pimp. The usual age of coercive entry into those systems for prostitutes is 12. The age of coercive entry of girls into prostitution and trafficking is 8 or 9 in many other parts of the world.