Rondo's lack of shooting wasn't a problem next to KG. There was one Finals series against LA where it hurt Boston but for the most part it didn't prevent success. I'd love to have that problem in the Finals though as it's farther than we've ever made it in the Sac era.
The spacing can come from others. While it's a preference for your PG to be a floor spacer, it's also a preference for everyone to spread the floor to a certain extent, although not a necessity. Realistically you won't have a spacer at every position. If MLM can continue on the path we all hope he can, there's one floor spacer. Then we'd obviously need a SF who can spread the floor. Just like in Boston that should be enough. It's not like when they were running out Perkins next to KG that he was spacing the floor at all. Not every position 1-4 needs to be a shooter.
But no PG is perfect. Aside from the Lebron/Durant level, no player could really be deemed as the perfect player without at least a weakness or two. Even Wade isn't that great of a floor spacer. I don't understand the need for Kings fans to constantly harp on one or two weaknesses from a player while ignoring many of the strengths a player brings, then turn around and many times ignore the weaknesses of a player on our team they like while focusing on the strengths, or vice versa actually. Many times if a player is liked, weakness are ignored but if a player is disliked, strengths are ignored. We saw this often times with Reke, ignore his strengths then build up the strengths of another like George Hill, Vasquez or even Augustin(all promoted as replacements at one time or another) while ignoring their weaknesses.
MLM's lack of ball handling and his defense thus far are both considerable weaknesses but most still want him here. Vasquez has many more weaknesses than Rondo. Same with IT. Same with just about every player on our roster outside of Cuz. Yet Rondo still impacts a game more than any player we could throw out there aside from Cuz. Basketball is a chess match and a team works as a machine with multiple parts which fit together. You bring in other talent to makeup for weaknesses. Rondo has shown at the least he's an AS level PG with or without a jumper, a jumper which has improved btw. But his lack of a jumper isn't a reason not to make a move for him if that were possible. He's too great a talent too pass on. What you do is plug another shooter into the lineup to help cover for Rondo's weakness. It's the theory that you get 2-3 clear foundational, star pieces and surround those 2-3 players with support players who fit around them, not to instead worry about how a foundational piece fits with the support players. That's backwards. It's much easier to put shooters around a guy like Rondo than to do the reverse and get a guy like Rondo here in the first place. Shooters are easier to come by and attain than top 5-7 PG's.
If Rondo's shooting was such a weakness, teams would just sag off him and he'd struggle, change the complexion of games. Yet that doesn't happen all that often. He still gets into the paint when he wants. Still gets to his spots. Still a top 5-7 PG when defenses decided to sag 5-10 ft off him and he now can hit the 15 footer with some consistency. It's far different than when defenses sag off a guy like Vasquez or even Rubio. That does close down penetration for those two although Vasquez can barely penetrate at all, ever. Rondo time and time again has shown he's crafty enough to still get to his spots no matter how far off the defense plays.