Graphic designer here,

In-depth explanation below:

There's a 1 inch margin between the edge of the bag and the outside edge of the cookies on either end. Normally you leave a 1 inch space from the edge because it stretches and distorts the graphic you're printing if you don't.

They could have gotten rid of the arrow cookie, but the other cookies would have needed to be re-centered on the box, leaving the Xbox cookie floating by itself on the margin where I assume it needed to be...again because of the 1 inch margin.

TL;DR

This was a margin spacing issue with the edge of the box, they had to fill the empty space on the box somehow. Otherwise things would look weird according to a bunch of conflicting rules in graphic design.