It's not just about hitting a jumpshot.
A lot of people are fixating on Rob's jumpshot. Sure, it would help him become a better player... but that isn't what is stopping him from becoming a reliable facilitator like the OP wants. His complete inability to create his own offense is the big roadblock. And to be honest, I haven't seen much evidence that it's in his future either. He doesn't even try to do it in games. Once in a while, guys will surprise you - nobody saw Jerami Grant morphing into a borderline all-star after his first few years in the league, for example - but skills very rarely just appear out of nowhere like that.
Rob's passing is a nice tool. It helps us. Occasionally, a team will be poorly-prepared for it, or the ball will just bounce the right way... and he'll kill teams with it on those nights. But it won't be the hub of any offense. That just isn't realistic to expect IMHO.