The problem with pro-porn feminism is it's inherent selfishness. The issue is not about us enjoying sex (yay for that!) -it's about an industry monetizing our bodies and our sexuality. When a "feminist" pornstar says working in that industry makes HER feel liberated, that's very shortsighted. While it might build her up personally, it pushes the rest of us down. It tells society we're all still just f*ck dolls and perpetuates the role of women as mere "pleasure givers" because even in 2-D we're there just to satisfy someone else's sexual needs. The ripples that a porn culture creates will affect all womankind for generations to come.
Pornography dehumanize those participating in it, especially women. Therefore, if the goal of feminism is to elevate women above a subhuman level, porn and feminism cannot co-exist.