It's also worth noting how the development and production of an animated feature differs from live action. The script rarely makes it to screen fully intact. So much of the story is "discovered" in the boarding and editing process, because the film takes so long to be "shot", typically 18 months to 2 years (or longer). Sometimes the third act hasn't been figured out when the first act is nearly finished. I've seen it first hand.

Apparently, Wes Anderson didn't come up with the whole "whack bat" sequence until they were well into production on Fox.

Not only is the spec market for animation a long shot, the life cycle can be brutal.