Well, to begin with, I’d argue that the only people that are truly “modern jazz” - that is, making modern music that came out of the jazz idiom that seems to be true to the spirit and ethos of jazz - are people like John Zorn, Anthony Braxton, the whole Downtown NYC scene (Matthew Shipp, Susie Ibarra, William Parker, David S. Ware, etc.), Ken Vandermark, and likeminded people. And this might be controversial (or might be accepted as a given), but their entire careers (save Zorn) have mostly been predicated on emulating Coleman, Ayler, and other Free Jazz heroes even down to the way that they do their album art and layouts. That’s fine, but a lot of these guys have come dangerously close to “Tribute Band” territory.
I think that John Zorn and his Tzadki label were the best thing going in modern jazz for much of the nineties, and really reached an unparalleled sense of community and creative homogenity - Zorn’s records, which were mostly great, acted as the nucleus around which solo records and compositions from the component members of his groups circulated like electrons. Sadly, that label seems to have collapsed into navel-gazing, with Zorn seeming to strive for inaccessibility and releasing a glut of pointless, uninteresting records.
I thought that Chicago Underground (Duo, Trio, Quartet, Orchestra) throughout the late nineties and early 00’s, were really onto something. Though they’re mostly known as satellite members of Tortoise and that whole Thrill Jockey scene, those records were incredible modern jazz efforts that were listenable as hell while still being challenging and interesting, especially with the incorporation of electronics and electronic processing of some of the natural instruments. That Chicago Underground Quartet record remains one of my favorites in recent memory, and one of my favorite “middle of the night” records.
My main beef with a lot of the modern jazz groups mentioned in the OP is their reliance on novelty; Brad Mehldau’s entire popularity is based around the fact that he did “wacky” Radiohead covers. Ditto for The Bad Plus, who seem to be enjoying a streak of popularity based on jokey post-bop Nirvana songs.