It all goes back to the purpose of cartoons. The purpose of a cartoon is simple: it's to blow the audience's mind. Nobody ever watches a cartoon, or any form of entertainment for that matter, with the intention of seeing something tepid that just passes the time. People want to be transformed and exhilerated. Even after a long day of work when you flop down infront of the TV and your standards are as low as they'll ever be, you'll still find yourself hoping to find a diamond in the rough. Timing isn't capable of delivering a diamond any more than a really good set of tires can drive you to the grocery store. Timing is just timing, something vital that takes its place among other vital things. Good timing plus drek does not a good film make.
A common story in recent animated features has a bunch of animals run away from captivity to pursue their dreams in some far away haven. How do you blow minds with a story like that? Is the premise intrinsically mind-blowing? No, but you could argue that some classic comedies had plots that were just as thin. Are the characters themselves "great" characters? Probably not. Are the gags strong enough to support the film? Well, maybe they're not THAT strong. It becomes clear when you look at the pre-production art that the backbone of the film, the thing that everyone's hoping will save it, is the timing.
The thinking is, tighten up the story, the animation and the editing as tight as they can possibly be and all the other problems will go away. But timing wasn't meant to bear that kind of burden. Timing is no substitute for charisma or imagination or street smarts or nobility or fine acting and animation or gut-satisfying humor and story. Timing is just timing.