This change, just announced today by John Lasseter and Ed Catmull, will take place in Walt Disney Co.'s Burbank studios, leaving Pixar to exclusively work onCGI projects. There isn't a specific answer to why the change happened, but one rumor centers around Chris Sanders who is responsible for Lilo and Stitch and the upcoming film American Dog. Lilo and Stitch, if you can remember, was hand-drawn -- and was a huge success. Perhaps they're hoping the same hand-drawn success with American Dog.
I do think it's nice to know that there is an effort being made in preserving this art form. I often times get worried with how great technology has become that we get further and further away from our origins. Being a bit of a technology dunce I don't understand the steps necessary in making a CGI film but I do fondly reminisce about the making of Steamboat Willie. I still vividly remember watching how they drew out the story to create the film. It was exciting seeing the characters come to life right off the page. I find relief knowing that there are many films to come made in that same historical way ... and I'm sure many animators are relieved too.