I'm not familiar with Jamal's recent work but am I correct in my impression that he no longer plays in the style that was so popular?
I think that one of the things Davis doesn't take into consideration is that there are fashions in criticism (as with anything else). In the hey day of Jamal's popularity you couldn't make much of a name for yourself by liking him. Only Miles would have dared do that-- and he may have been trying, as he often was, to be contrary. (Probably not-- he seems to have genuinely admired Jamal and was certainly influenced by him). Anyone that popular is bound to be dismissed by those of us wanting to seem hip. Also you just heard too much of it at the time. This even happened to Art Blakey. I remember writing a review of a performance of the Miles Davis 2nd great quintet and referring to Wayne Shorter as having "recently escaped the confines of the Jazz Messengers". I probably saw Blakey a half dozen times over five years and got tired of hearing "Moanin'".
In the early '60s this seems to have been the fate of any jazz musician who became too popular to be dissed by critics. The one exception of course being Miles.
(This still goes on: Moms recently bad mouthed Robert Johnson mainly because he was the only bluesman most people know of. The "King of the Delta Blues" stuff may be over-hyped but Johnson is still pretty fucking good.)