They're out of touch. Gangsta rap culture is long dead in the black community--just look at the athletes now, its all about the hipster look.
The "hardest" rappers out there, if you can even call them that (Wiz Khalifa types), are more about smoking weed than any real crimes. Of course, squares still think that is a real crime.
I mean seriously, Kendrick Lamar looks like he comes from the set of the Cosby Show. This is the culture that is killing black youths?
Not even the survivors of that era are anything close to offensive.
To be fair, it was not always like that.
A guy like 50 cent grew up as a crack dealer, got shot like 8 times or something, and ended up breaking through in the early 2000s.
I think rap has changed now, but conservatives still like to think of it as some great scapegoat or corrupter.
Equally as interesting is how liberals seem more supportive of it, when the vast majority of rap (macklemore is a pop artist) is anti-gay mentions guns frequently and glorifies the objectivization of women. I would imagine there would be some cognitive dissidence there.
However, returning to the O'Reilly's of the world, I think it's simply an inability to adapt to new things and new culture. In reality, all music over the last 50 years has been centered around partying, women, etc. In reality, there is little difference in the topics, but the presentation is much different. O'Reilly probably has an inability to appreciate new presentation despite the underlying message being similar.