Evolved is definitely not the best word of choice here.
Evolved is usually used in a positive sense.
At best you could say it's changed.
It's degraded. And has stagnated. Stagnated in a state of degradation.
An important thing to note with Dre's comment is that he still stated "if you don't like it don't listen to it" "I dont listen to most of it." It's very clear his stance.
The lack of musical quality aside, let's take a look at the character...
Hip-Hop / Rap, it used to be;
- tough
- intelligent
- Big
- drug sellers
- witty
- class
- individuals
Now, Hip-Hop / Rap is about;
- unintelligent
- drug users (as in 'druggy' type shit, not weed)
- little. Baby. Yung
- skinny / sissy attire and stature
- gossip
- acting like 15 Yr olds is the aspiration
- clones / copycats
Image conveyed by the old;
Rough life/background, tough from the streets, educated and built themselves up, not to be messed with, found a way to make money and reach success. Intelligence. Respect. Grown men/women.
Image conveyed by the new;
Spoilt children with attention disorders who get sent out of class at school. No class or respect, snitching rats. Medicated and uneducated, nitty substance users, whingey dribbly attention seeking entitled child divas.