Most beats are terrible. Most bay producers are literally tone deaf and should give it up cause music isn't for them. It doesn't help that the fans here eat up the played out 2004 sped up soul sample chipmunk beats that Berner and amp be using. Some are alright but Just cause a beat has a sample in it doesn't make it good. There are good bay producers out there it's just rappers nowadays don't wanna pay for beats. They don't want to pay for studio time, or mixing, or mastering, or album covers.
That cost cutting mindset carries over to the final product which ends up being shit. How many bay albums out there would a major label A&R listen to and think "this is a professional major label quality album"? Yeah.
It is two separate problems
1. The tone deaf producers
2. The talentless MCs
Both have gotten increasingly prevalent since the 90s, however, since they are separate and not completely correlated issues, it has gotten to the point where even the competent MCs have mostly unlistenable beats. And that includes pretty much everyone who was listed in this thread as supposedly "still holding it down" for the real music - you can find plenty of good MCs to point to and say "see, it isn't dead" but the reality is that even those dope MCs mostly make shitty music because of the beats. If you can ignore the beat and only listen to the verses, then more power to you, but I personally can't do that.
Now, that the beats suck is a direct consequence of the oversaturation of the scene with both artists and releases per artists - all those classic albums in the 90s were made either by in-house producers who dedicated all their energy to their in-house artists and as a result were able to establish their own sound, or by a handful of widely used producers who, however, didn't have hundreds of artists to work with and dissipate their creative energy on, so they were mostly providing quality material too. On top of that, there is the impact of the change in copyright laws in the mid 90s and how sampling got much more difficult as a result, then there is the shift from the 10-track album sold out the trunk that had to be dope all the way from start to finish if it was to move units to the 20-track album with 2 solid singles to carry the sales, 13 filler tracks and 5 skits; the consolidation of radio stations across the country that resulted in the disappearance of the local styles and a long list of other negative trends, not just in hip-hop but in music and society in general.
But ultimately that matters little, those aren't thing that it's in the power of anyone to change, so unless the model of making and distributing music changes completely into something that just forces the artists to make good music by just keeping the BAU course, it will remain this way for the indefinite future. Problem is that it will always be what the people want to listen to that will determine what music will be made, and if the masses have been conditioned for long enough to listen to and like shitty music, then shitty music is what they're going to demand and shitty music is what's going to be made. A trap from which there is no escaping and the window of opportunity for preventing that is rapidly closing as time passes