A layout artist must make more room, not only for aesthetic reasons, but to give the animator room to move the characters around in the scene. If everyone is already so close that they are almost touching, there is no place left to move. Imagine your whole family stuffed in a closet trying to yell at each other. You couldn't wave your arms or throw pointy things like you'd need to.
Making space is partly creative and partly functional.

All through my storyboard Donald Bastard keeps changing sizes. Sometimes he is smaller than the boys, as he should be, being a fowl, and sometimes he is as big as them. So as a layout artist, I'm going to correct that the best I can.

SEE DONALD HOP THROUGH THE MAGIC OF CHEESY TECHNOLOGY
still more to come...