The Chicken Little DVD cover conspiracy

Earlier today, I was helping my brother set up our DVD player so he could watch Chicken Little. This movie, for those of you who don't know, is a modernized version of the classic Chicken Little story, made by Walt Disney. The film centers around four main characters: Chicken Little (who is a chicken), Abby Mallard ("ugly" duckling), Fish Out of Water (fish), and Runt of the Litter (pig).
But, like I was saying, I have the DVD. This is what the cover looks like:
Notice anything missing? Yes, that's right, Abby Mallard is conspicuously absent from the DVD cover, being replaced by a porcupine that literally has one line in the movie (and preview).
I don't understand the marketing techniques used here. Sure, the brief moment that they showed this porcupine personality was a funny one, especially for a kid. But what I don't get is why they would choose to take the second place star of the movie out of the picture in order to put him in. I mean, come on! There are even two disembodied hands on the cover! But no Abby. I feel sorry for Joan Cusack (John's sister), the actress that voiced her. Poor lady.