Currently: box sizes are predetermined with only a specific amount of choices available for retail sets (I think there's about 7 choices). It was done this way so that every set wouldn't have a custom box size based on its part count. Sometimes this means that a set might be just too big for a smaller box size but may seem small in a bigger box size, but since there's only the limited choice to make sure the boxing machines don't have to be reset constantly you'll end up having this bigger box with what feels like less pieces.
The whole system is currently being evaluated. We are conscious of the environment for sure. Remember that the current system is the one we put in place to help save the company from the mess we were in back in 2004. Now that the company is healthy again we're able to re-evaluate a lot of things again, but anytime something is implemented it lasts a few years no matter what.
Steve



