I agree with Aaron. It doesn't matter who the director was, the studio was going to play things as conservitively as possible with these films. It is why Gilliam had absolutly no chance of directing these films, since he always takes risks. To be honest, Columbus probably did a far better job...
Well, with big properties like this, studios tend to get conservative. They set out to not fail, rather than make a great film. Better to have a bland but steady director (Columbus) rather than a flamboyant, but unstable one (Gilliam). It is why we get a movie that is a slave to the books...