You're not missing anything. The reason Cook has interest from the NBA is that athletically he could rebound and defend out to the 3-point line, and can finish near the rim. Many guys have made good NBA careers out of that.
Before everyone says "he can't shoot," "he turns it over too much," "he can't pass out of of the post," stop. You aren't wrong, but he would not be asked to do those things in the NBA (or at least not nearly as often as he has to do it at Iowa. He is one of our 2 best post players, but it also the best on the team at going off the dribble. So he gets put in situations where asked to be a playmaker and not just a finisher.
I have really no idea if he will make it in the NBA or not. My opinion is that he will be given an opportunity to do so. But if he does make it, it won't be because his outside shot got better. It will be for the other reasons I stated above.