It's that anti-dead person thing, like 'oh man, this well respected producer is dead so now I'm gonna be all controversial and say he aint all that'
Boring. I've outlined why he's a great producer.
If he was alive, I'd also be saying he wasn't all that. Of course, mind you, I'd probably be doing it a lot less often. Let's kind of break this down.
His era of producing for Tribe. Now, no offense, but the Q-Tip/Ali team is just as good, if not perhaps better than Dilla. Or at least, were in their prime. Dilla is responsible for making the music that caused Tribe to fall off in the public eye. Oh sure, you could blame Puffy for it like everybody else who wants 'to be down'. You could even use the more logical argument that by this point, Tribe was sick of each other just a little; but it doesn't help that he was essentially made navigator of a sinking ship.
Also, his production for Q-Tip solo was laughable, not to mention those songs he produced were offensive and naive. Q-Tip went from being founder of the "No-Fun Club" (I.E. Common, Blackstar, etc.) in which it's all "Roots & Culture" above all... and then, he's selling out as gratuitously as anybody in that era. Which is fascinating, because Jungle Bros. who were always both commercial yet positive simultaneously got phased out for their more dramatically 'positive' groups like De La and Tribe.
I'm not saying the man didn't make good music. But his death caused a lot of historical revisionism. I pointed out earlier how KRS-One rewrote the history of "Criminal Minded" to keep Scott La Rock in the legend of his career. But that album is a Ced Gee/Paul C project.
Dilla's death, however, caused everything he worked on to suddenly be 'under appreciated'. Some of it was just NOT GOOD, and people knew it.