Why rape someone if already getting off?  Most people who rape are not committing a sexual act, but rather are involved in an act of power.  You would have to be a minority type of rapist to actually enjoy the act of it... and you would have to be a repeat offender to get to that point.  Chances are these repeat offenders are not watching a lot of porn because it would take a tremendous amount of effort to avoid the arms of the law.   Pornography gives the voyeur a sense of power, therefor lessoning the reason for power based aggression.  The Gloria Steinem analysis is far off!  It is frightening that these opinions are being toyed with by the law.  Case in point would be the Giuliani administration... who spent a lot of energy doing the bidding of his fascist X-wife and feminist Donna Hanover.  New York erupted into a test case for police brutality and oppression as a result.  While petty crimes decreased, infrastructural violence increased.  It might also help to understand the nature of libidinal energy.  A read of the "Accursed Share" by Georges Bataille might be of help in understanding the nature of excess sexual energy and it's need for waste.

http://en.wikipedia.org/wiki/Accursed_share