Yeah, way to act like a baby...
Yes, the plan would be to build around a guy who even with those flaws would be the best player on the team. I'm not for trading like eight firsts for him. But if the cost is mainly those guy and present draft value, then you can build and still be flexible.
The Spurs' problem isn't shooting. The Murray, White, DeRozan, Johnson Poeltl lineup's problem shooting. The White, Vassell, Johnson, Simmons, Dieng lineup has good spacing. The problem is that their main perimeter players struggle with shooting, making it hard to put shooting around them. Shooting will only really be fixed by subtracting more poor shooters than you add, and this deal is a net-two shoooters upgraded.
Mills is actually a good player. His FIBA performance is showing he's still fine physically. Obviously, him being an icon of Simmons' home country helps. And as I said in the above post, I don't necessarily want him back, but he'll probably be back anyway. May as well figure that into off-season plans, since he'd end up blowing them up by randomly eating cap space otherwise.