@Tokoro:
It really is hard to say why Pixar wants to go the "play it safe" route
No. It's really easy. $$$$$$$
Its show BUISNESS, not show ART. That they happen to make art is a nice bonus. Sequels are pretty much guaranteed to get the take of the previous films, and then some. Not to mention refresh the merchandising and the sales of the original film. Plus, they need less development time because the main characters and settings are already in place.
Don't forget, Monsters U wasn't on the schedule until Newt was scrapped, leaving a big hole in their schedule, AND it was originally also going to release in 2012 a few months after Brave. That they've pushed it back 9 months to keep it at one film a year, and they've already announced that the 2014 movie will be all new, say all that needs to be said.
And I'm fine with that. most of their movies are pretty un-sequalable. We're not going to see an Up2 or a Wall*E 2 or Ratatouille 2, and even though Incredibles 2 is possible they haven't shown any inclination to do it.
A couple sequels are just there to give some guaranteed fundage while giving time to develop other projects. And "sequel" isn't a dirty word if theres an actual story to tell. People want to see characters again, go on new adventure again, and with the origin out of the way, you can really cut loose and shoot for the stars.