How do we know that Iguodala is not a superstar? He may not be recognized as one, but a lot of saber stats love him. He scores efficiently (hasn't taken 20+ shots in a game this season), involves his teammates (as shown by his AST numbers), crashes the boards, plays great defense, etc. He may not be recognized as a superstar talent, but I really do think he is. What he lacks on the offensive end, he more than makes up for by consistently playing great defense. Just look at the Miami game. His box score looks like he did very little, but then look at Marion and Jones and you can see Iggy's impact.
As for Miller, I'd rather let him walk and either use him in a S+T or just use the MLE to replace him (Bibby and Sessions could both hit the open market and I think both would be better fits).