Maybe what you fail to realize is it is 2 different types of rap. Guys like NWA, Cypress Hill and Run DMC were originally hip hop, that was more defining of a culture and often made music with a message. The common, most successful form of hip hop/rap now has a mix of pop with it, which is what gets radio play and potential for concerts and big record deals, since this is what most people rap for. And Chris Brown technically isn't a rapper.
Point is, the first guys you mentioned are responsible for the current state of hip hop/rap by cosigning and affiliating themselves with the current top stars. Lyrically, none of those rappers you first mention will be widely regarded as GOATS, neither will the latter.
But, when you take guys like Nas, a true lyricist, you still have records like "Owe Me", "Nastradamus" & "Oochie Wally". Reason for that is the old school style of hip hop isn't in high demand. People want club based records or something that sounds good in a car. It's all about being commercial and marketable. I'd take the last 15 years of hip hop/rap over any other time period, I don't want to hear depressing music about the struggle, I want the upbeat, party records. The songs that showcase the good life and can be used as a form of motivation.