Agreed, free throw shooting is on the player, but the need for it comes from the coaching. If the coaches don't stress the need for at least 70% free throw shooting, the players are not going to spend additional time getting to the 70% mark.
If one or two players were bad at free throws, I'd just blame those players. With the entire team bad at them, it comes down to coaching and stressing what is important.
And what I know of Morrison, is that he hates the role he has been relegated to. He wants to be the star player and go-to guy he can be, its the coaching that is putting him on the bench and not giving him opportunities. Once he gets on a roll, he gets pulled for Thomas. How is that supposed to give confidence and aspire you to produce? And what I know of Morrison does not come from interviews and the general media, but a much more personal source.