Wasn't Rick Berman in charge of TNG just when it began to get good? Or am I one of the few people who think the best thing to happen to that series was Roddenberry passing away, god bless his soul?
Anyway, yeah, McCallum gets too much shit. He was just doing his job. And he did a great job! He wasn't meant to be there creatively, he was more like a production manager, and the amount of management he had to juggle was mind-boggling, and each film came slightly under budget and schedule. Hell, he made Episode II without a script! Can you imagine the logistics? On top of which, he subtly prodded Lucas into more useful directions, like bringing in a dialogue coach in Episode III. The fact is, Lucas was the boss, and he wanted someone to carry out his wishes. McCallum knew this, and had he resisted significantly Lucas would have fired him and found someone capable of that. Howard Kazanjian doesn't get shit, but he did the exact same thing. Why? Because that's how it goes. Anyone who hasn't had to do their incompetant boss' bidding hasn't spent enough time in the work force. Some producers want to be in on the creative side, and some enjoy being managers and taking a backseat. Arguably, the prequels needed that guy, but Lucas was the one in charge and he wasn't going to let that happen.
On top of which, McCallum started out with a bang with Young Indy, not to mention Singing Detective. Great series. "Want to do the prequels?" Hell yes, where do I sign. I think he acted in good faith, George Lucas was a god and these were thought to be the biggest films of the century, but after Episode I he realized, "oh, damn, all those doubts I had during production were true. Oh, well. I'm under contract now. What's the point of quitting?" No one goes after the producer of The Green Lantern. "WHY DIDN'T YOU MAKE SURE THE FILM WAS GOOD??? ARGHHH!" But Gary Kurtz sets an unrealistic precedent. And look what happened to him? He was fired, and after one more film that was the end of his career. If McCallum had any incling to be a creative head he would have got into directing. He was interested in management, and to that end he did a fantastic job.
I wish him well. And I hope he winds up on better films. He deserves it.