First of all, what you described is not gangsta rap, it's commercial music in it's entirety. It's also a reality - it's what they relate to since being int he position they're in.
Stop making excuses for Will, why would you think that's it's just a PR attempt? Because you feel that is is? Because you don't want to believe that he feels otherwise and likes something that YOU didn't think he would? Please. Dude's a grown man, if he can go on record with Snoop Dogg or say that Dr. Dre is a producer that he'd love to work with, support a movie starring T.I., or that he listens to 5.0 Cent what makes you think that he's just saying that for good PR? If Will is as genuine as you'd love for him to be, then you need to accept the he was genuine in what he said.
Plus, look at Wills videos, that checklist also applies to him as well ("Party Starter" being a perfect example), he's also rapped about those same topics himself so he's not a saint in that right at all.