You cannot compare Kanye to Brian Wilson or Syd Barrett. Wilson and Barrett composed original works.
Kanye, and the rest, look for a catchy music riff to sample, add a heavy bass track then liberally sprikle with clichés. Nothing a computer couldn't do.
To take a genre seriously, you must have some element of music composition. You'll find it everywhere else. Taking five or six catchy bars from someone else's composition doesn't count. You'll notice that classical often takes a riff and then turns it inside out and plays all sorts of tricks with it through a composition. Better rock bands do the same. That's musically interesting. You can't just repeat the same phrase over and over, that's boring. Bananaphone has more musical depth than any rap song I've heard in the past ten years.
Musicianship is another issue. Rappers are not musicians. They can't play instruments, nor could they switch genres. Serious performers, typically, study many genres. You could take a good opera singer and drop him into a rock band or jazz ensemble. A traditional African drummer could back a country band. And a fine guitarist can cover jazz and rock out. Rappers are totally one-dimensional. They can't play other genres and neither can they actually compose music.
This is why rap gets very little respect. If a rapper started composing riffs and played them on instruments, a lot of people would take notice. Similarly, the lyrics would have to get away from the database of rap tropes. And if they actually learned to sing - maybe occasionally knocking off small performances in other genres - that would be remarkable. But that just doesn't happen in rap.
The typical fans are another problem. Music education is almost dead. When you're handed an instrument in elementary school and play a wide variety of music, you learn a lot. Most of the teachers will give you an intro to composition and explain a lot of what's happening in the music. I had a great youth and teacher who took us through every element of a traditional march. Others went into classical, jazz, rock, and much else. The more you know about music, the more you appreciate it. But if you've never been exposed to the how and why you'll never understand why some is good and some is bad. You'll just look for something with a danceable beat and completely miss out on a lot of wonderful music because you don't understand it.
In lots of ways, there's a monstrous appeal to ignorance in today's society. You have people who know nothing trying to equate their ignorance with others' knowledge. That their opinion deserves the same consideration as any other despite knowing nothing. Further, some are quite proud about knowing nothing because those who do are "haters."
That's a bunch of crap.