Replacement of AI with Mentats (as well as other narrow specialities) has done nothing but disfigure the soul. We see few Mentats -- aside from Paul and eventually another -- who are not constricted. Similarly, if you practice medicine, well, you get the Imperial Conditioning. Certainly, a sign of trust ... but also a sign that the person's actions are no longer completely free.
Now, I am not touting the Heinlein "A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship ..." line, exactly, but the alternative to AI is the kind of stagnation we see in Dune, millennia of locked down ritual, honed again and again, with some people becoming ... utilities.
Before we begin this jihad, we must examine the alternative futures.