Here lies part of the problem. You say rap, but the actual movement that has been revolutionary is the hip hop movement. MC-ing is just a component of that movement, and to reduce MC-ing to what Lil Wayne (or anyone) has written is ignorant. Holding an entire genre guilty just because of one 2 Pac song does in fact degrade the importance of the genre unfairly.
To call Chuck-D an "outlier" is also incredibly ignorant. Tons of rap is culturally conscious, political, and sociologically relevant. Arrested Development, A Tribe Called Quest, Fugees, Wu Tang Clan, Etc., Etc. So your general point is rightly criticized for painting with broad strokes.
Why, exactly, do you not think he is a musician? Are Thom Yorke and Maynard Keenan not musicians either? Trent Reznor? Do these guys have to pick up a traditional instrument to be considered a "musician"? Does Chuck D have to utilize more melody to qualify as a musician?
...as compared to who? Mick Jagger? Layne Staley? David Gahan? Not sure what you are saying here. Does spoken word somehow not count as vocal musicianship? If not, explain why.
Okay, here you go: These performers are every bit the caliber of artists that are out there in other genres writing and performing their music from scratch. Not only is that fine for me to say, but it is commonly considered correct by anyone who has written a song or prepared a show in their life. It is always non-musicians that voice opinions like yours.
It may not be racism or intelligence. It may just come down to ignorance on this particular topic, and that ignorance might be widespread and common. Not only do you conflate MC-ing with the whole of hip hop culture, but you mention punk as if there is nothing in that genre to be ashamed of when every punk band in existence ripped off Chuck Berry's formula for rock music using the same tools since the beginning. Punk even ripped off all of their subcultural elements from the raggae movement that preceded them (simple song construction, subversive personal style (the mohawk apes the effect of the dreadlock), conflicts with local authority, etc.)
If your point is that sampling is somehow a class below formulaic rip-offs with the traditional instruments, then explain why it is you think that. Because as it is, sampling is just as innovative and musical as anything that has come out of punk. A sampler is just as much a tool as a guitar or drum kit, and if there isn't a racial element to your point then it is unclear why you think these tools reside in some sort of imaginary hierarchy.
Pointing to top-selling rap is not "digging". It is the most superficial, easy, half-assed effort you could possibly offer. It is biased googling with no hint of research.
Digging would be listening to GZA's Liquid Swords, Madvillian, or The Cold Vein by Cannibal Ox so you can actually have some sort of claim of being up to speed. Digging would mean you apprehend not only the existence of instrumental hip hop (records that only have DJ-ing), but that you have actually listened to albums like Endtroducing, or Krush, or Beat Konducta. Digging would mean looking into the history of graffiti artists and break dancing to actually flesh out your understanding of what hip hop culture actually is, and the people that it comes from.
Your version of "digging" thus far is equal to suburban housewives getting up in arms about how "satanic" metal is just because Ozzy took a bite out of a bat once on stage, or not letting their daughters go to a Lady Gaga show because she performed with blood stains on her crotch. If you are honest about the negative aspects that you mentioned (greed, drugs, misogyny), you will admit that those elements came after the beginnings of hip hop. You will study the history of MC-ing, then you will admit that those elements became popular in hip hop because white, suburban teenage males are desperate for a tough identity, and that it is they who drove the sales of the popular rap albums that you listed above. Not black kids.
Subcultures don't just buck trends. They produce new genres that alter the course of mainstream culture. Hip Hop itself has experienced dozens of revolts and rebirths since it's birth in the early '80s, and your insistence on only pointing to gangster hip pop as representative of the entire genre is always going to be insulting because it shows that you are not interested in really apprehending what's out there.
All that you know about rappers is that they made some records. But who bought those records? That is the real question here. What market were they catering to? Because it is always markets that move records. Not content.
So do you take metal seriously after listening to Limp Bizkit? Do you take rock seriously after listening to Maroon 5?
Anyone can point to popular, terrible examples in any genre. So your point here is incomplete at best.
