I found this as part of an interview that Victor Navone did for some blog – a decent interview but one answer caught my eye. I thought it neatly summed up why Pixar is so successful, and why their films have always done so well.
This answer here: The company is run by creative people – John Lasseter and Ed Catmull – and not by business executives. They know how to make movies and how to support artists, and they’re not willing to release mediocre films just for money. We have a very collaborative culture, a spirit of openness and communication between artists and departments. There’s not as much politics and manoeuvring as you will find in a typical Hollywood studio.
A lot of different people have commented on how successful Pixar is, and why. I think Navone nailed it pretty well.