What do you miss about old school hip hop music and why?

My answers are quite similar.  First, I miss the diversity of styles, and in particular the concept that hip hop could just be fun and about the music itself.  In the 80s and early 90s, there were artists / groups that achieved commercial success without being subsumed by concepts such as guns, b!tches, and benjamins  - Digital Underground, De La Soul, Das EFX, A Tribe Called Quest, Biz Markie, Slick Rick, 3rd Bass, D Nice, etc.

Next, I miss the respect afforded to the lyrical masters that defined hip hop as an art form  - Rakim, Big Daddy Kane, KRS One, Kool Moe Dee - I am skeptical that these artists could have achieved the same level of success today.

You are right! I was a Big Daddy Kane fan. I also like groups like Souls of Mischief and the Hieroglyphics. They were not consumed with the material things of life. It wasn't just the hits it was the songs in between.  Kane had a song called "set it off"where he had a line that said "e e e e even if I stutter I'm Gonna still come off". He put a stutter in his rhyme. Witty. I missed the King Kong type confidence and energy in the music and rhymes.

Remember when rappers would have impromptu competitions against each other? Whoever had the best wordplay and rhythm could disrespect the other guy off the stage.
 And the crowd would go crazy.