Thinking a little more about this, I'm not so sure what the OP is getting at. There is still a lot of stuff happening, such as:
But, you have to go to NYC, Boston, or LA to hear the more cutting stuff.
If you are asking why we haven't produced the next Jaco or Marcus Miller recently, don't know what to say. Certainly the "Music Business" here is no longer promoting that kind of music as much anymore.
If you are asking why the shows you heard were similar to shows 10 years ago, I also don't know. What were the artists hired to play? I am sure Marcus has kept active doing new stuff. Maybe that's not what he chose or was asked to do.
Mike Stern? I don't know. He is still so far ahead of most cats, I wouldn't know where he is at.
You know, there are a lot of guys I wonder what has happened to them. Entertainment is brutal business and bills have to be paid.