Both BI and Zo are like 38% shooters on 6+ a game. They are both very very capable shooters.
Simmons going from basically 0% on 0 attempts to even 30% on 2 a game would be a huge leap. It would also be a leap that wouldn't even help him. He'd have to take a historic leap to become even remotely threatening from deep. Which for a guy with very little touch outside of 3 feet and zero FT skills, is hard to believe in.
I'm not interested in Simmons. Huge cost (did you see the deals Morey turned down?) for a player that, in order for him to fit alongside Zion, would need to be transformed into a completely different player.
Oh and he's also making $34m a year.