I think hip-hop is in a great place right now despite what most seem to think, as if there's a musical crisis is occurring right now and hiphop will die out from over saturation like disco did in the 70s (which, it really didn't die out, it just incorporated itself into other cultural facets in different ways we still reference today, like in fashion).
Hip-hop, I think, is at its most creative and branched out stage at the moment, but who knows where we might go. During the 80s and 90s distinct styles and sounds took decades to form because of regional disparities and geographical separation. But now with technology, communication and the internet fast forwarding all aspects of our lives, the music changes with it, and now we have constant changes and updates to rap every month of every year and new styles developing at break-neck pace, with more diversity than ever before. And I think the internet and its fluidity will allow hiphop to keep developing, adapting and changing with the times and never lose its shelf life a la Disco, or at least it won't for a long while. When people got tired of trap rappers like Gucci and Jeezy they went to Waka Flocka when he popped up, then to Future when he popped up, then Chief Keef when he popped up, then to the new wave of Yachty and Denzel and Pump etc etc when they showed up, and whatever becomes cool after them will replace them, probably in the next 1-3 years.
As far as the dilution of hiphop and the loss of substance? I'd agree maybe in the circumstance of mainstream hiphop, but even then, popular rappers in the 80s, 90s and the 00s were never really that lyrical or deep. Like Nas wasn't that popular in his day, the hottest songs of 94' were like by Salt n Pepa and 69 Boyz, Public Enemy weren't the hottest shit on the block in their day either, the hottest shit was all the hip to the hippity hop electro funk shit they had, yet they both remained as cultural icons and legendary acts. Sometimes substance and pop appeal does crossover, like in the case of a Tupac or a Kendrick Lamar, but they are really hard to come by and you can't expect every rapper in a generation to rap quite as well as they do. But for the most part, artists with more artistic value really don't end up mainstream, and thats in music in general. It's why Jay-Z ended up being a multi-billionaire and stayed afloat despite going up against Nas in the early 2000s. He could still sell records. He had the pop appeal. People still liked him.
As far as comparing time periods, which I think is better? I really can't say. I probably immerse myself in more contemporary records so I could say I like the new generation better, but I do think previous generations have a lot of timeless classics to offer. I think I'll just leave it at - music is a continuum - yes with eras and time periods and specific cultures, but still, good music just means good music. As long as hiphop continues to offer the most cutting edge, exciting music on the airwaves we've heard for the last 40 years of its history - then I'll continue to follow and support it.