Advancing a lovable supporting character to a lead role is sometimes a bad idea (i.e. Cars 2, Minions). But, when the supporting characters are far less annoying than the lead characters, it can be a good idea (i.e. freeing Puss in Boots from Shrek, and the Penguins of Madagascar from the rest of their zoo crew). Pixar's new Finding Dory must have been a tricky prospect, because so many people love Finding Nemo (it's one of the biggest moneymakers in the studio's history) and also because Dory could easily have fallen into a one-joke pattern (her short-term memory loss).