In coaching or for that matter in any field where you manage people and their behaviors you have to treat each person as an individual and give them different goals, instruction and training depending on your evaluation and assessment of how they fit into your organization's structure.
We don't have all the inside info regarding what JC has been told or not told by the coaching staff, but based on anecdotal and media coverage, plus what we all see on the court, it appears that JC is just getting the boilerplate mantra of "be aggressive/take your shots/be yourself".
If it is a fact that these are things he's being coached to do by the Cavs organization (and I have little way to know one way or another what he is or isn't being told) then this would be management and coaching malpractice.
Everything about JC's past indicates he needs to be coached up to strive for things like efficiency and assists. His track record indicates he is happy to jack up forced and contested shots until the cows come home, and he is not predisposed to pass on bad shots or to look for the outlet pass after he's drawn in the defense.
A player like Clarkson should be getting a much different message than guys like Hill who are reluctant and conservative in being aggressive. One size does NOT fit all.