At the risk of restating the obvious, American culture treats women horribly. And Rap is no exception—for a number of reasons.
It's a style of music that has zero investment in maintaining any kind of decorum. Not that there's anything wrong with that. In fact, it's what we love about it. People say what's on their minds, searching for the bluntest truth.
But the flip side is that their "blunt truths" might not be the most well-considered. It's an art form dominated by young men, in competition to prove their manhood. It's also an art form that celebrates the accumulation of status, and always has: chains, cars, and yes, women, who are treated like objects obtained through success.
Then you have strip club culture, one of the crucibles of hip-hop's development. And let's not forget the aforementioned "conscious rap," which has a strong strain of fundamentalist/paternalistic attitudes towards women. There's also the long-running pimp archetype, which hip-hop's pulp fiction fascination accentuates.
Add to that the limited roles given to female performers on radio and the press based on a general unwillingness to deal with the true diversity of female artists. In the hip-hop canon, women are still underrepresented by historians and publications, considering their lengthy contributions to the genre.
Then, of course, there are the artists who have histories of abuse or assault, from Dr. Dre to Big Pun to Gucci Mane to Lil Reese. And of course the industry more broadly, which continues to find time for Chris Brown guest spots.
This is not to suggest that hip-hop is inherently misogynist; like any culture, it's full of contradictions. But at the same time, it's self-evident that respect for women was never one of the core elements of hip-hop.