Mainstream Hip Hop follows the same tired and tried formula's as Modern Pop Music. "Rack City *****" is a great example. These songs have nothing to do with what "Hip-Hop" is, and there's clearly no artistry involved. It's just generic pop music. Call a spade a spade.
Hip-Hop is music with emphasis on the vocals and percussion. The amount of lyrics in a rap song are 4x the amount of your average rock song. This makes it a a great platform for vivid stories and imagery.
Song for reference:
Macklemore - Wings
http://www.youtube.com/watch?v=gAg3uMlNyHA
Amazing visuals painted lyrically about youngster's artificial infatuation with sneakers. How kids try so hard to be different, only to look like everyone else trying to be different. How meaningless the sneakers are yet how they play such a huge roll in peoples lives. The threats that go with sneakers (in the 90's). There's a nice twist at the end also. As an addict...he's still wearing them.
The song lacks technical-complexity and rhyme patterns , but the focus is on the vocal-delivery and the writing - which is excellent for any genre. The instrumentation is great, changing through out, with live instruments prominent.
Another example we could use is Tonedeff - Porcelain
http://www.youtube.com/watch?v=J2_wLfgF3yQ
This rapper has a extreme understanding of technical concepts in rapping. This song shines with its story though. It's a song about a junior-highschool crush that didnt work out. It touches on how what was so important young relationships are and how they scorn people for life. It's beautifully written and technically complex. He's rhyming at an extremely fast rate (never missing a rhythm), with complex rhyme patterns. He's rhyming words in the middle of sentences , words at the end of sentences, rhyming words in alternating lines, etc. Some have 7+ syllables throughout. Tonedeff also wrote, rapped, produced, and provided the vocals).
Bonus: Making of which he talks about the layering/sampling portion of the music (which he created using live instruments, and sampled afterwards:
http://www.youtube.com/watch?v=u3LamsjFgq0
Tonedeff also uses a rhyme pattern analysis "guide" called a flow notation system. This allows him to visually keep track and monitor the usage of rhyming words/syllables/et al. An explanation of the Flow Notation System can be found here:
http://qn5.com/tonedeff/fns/ and a example of a song using this system is here:
http://qn5.com/tonedeff/media/fns/fns_arch_01.pdf
And finally - An obligatory song by The Roots with heavy Jazz influence and some percussion. Yeah - They ALL know how to read/write/music.
The Roots - Rising Up
http://www.youtube.com/watch?v=6WbJ9Yc0whc
Both songs are worth a listen and are a far cry from "Rack City *****". There's alot more to Hip-Hop than just "talking into a microphone" and some of these guys have more talent than you can imagine.
A rapper rhyming at 13.5 syllables per second as Tonedeff did on the song "Velocity", is the equivalent of a guitarist thrashing away in the hip hop world. I can post songs where the emphasis is on complex rhyme patterns, or "emotion/feelings in the delivery", or the "speed" or "flow(timing)" of the words, or hidden/dual meanings and metaphors, or simply the story/message(lyrics).
Bottom line - with Hip-Hop music you have to understand that the focus is on lyricism. Does that make it good or bad? no it has its strength's and weaknesses like every other genre of music.