In fairness, he is a 50% 3-pt shooter.
I'm fairly sure Painter has told him to stay in the paint because that is how he has created his system to function. Edey might be on a fairly short leash in that regard. So he may be a better shooter than we know (but I doubt it).
I think what most people don't understand is that his height is not his best skill / attribute. To put it bluntly, it's his girth. Alot of other 7 footers are string-beans comparatively. Edey can put his back on the defender and take a step back, and he is just that strong to the point where you can't stop him from legally displacing you. Once he does that three times, he is now 3 feet away from the basket and is nearly automatic with his shot.
Everybody knows that if you can push him a few feet further away from the basket, his scoring percentage goes down, so defenders are trying to do everything in their power to do that, but more often than not, that involves them putting two hands on him and pushing with everything they have or trying to pin his arm down to help deny the entry pass. The problem is, when you are sitting there pushing with all of your might in one direction, then Edey gets the ball and is starting to spin to make his shot, you have to transition from full-push-forward to proper defensive form for the shot. The half second it takes to do that is not easy, and as a result, most defenders usually have an arm on him when he goes for the shot and it counts as a foul.
The only other option is to double him, but the rest of the Purdue team is good enough 3-pt shooters to make that option even less appealing. Edey has actually improved his passing significantly from last year. His assist to turnover ratio in the last few weeks has been in the 1.7 to 1 range while it was 0.7 to 1 last year.