It's pretty simple. If you open one case, the likelihood of pulling a good auto is smaller than in cases with a smaller auto checklist. (Even if there are an additional 1-2 good autos). It also reduces the value of inserts and base chrome because they have to produce more of those to fill the boxes that come along with the bigger checklist. Lose/Lose.
Can't wait till Chrome either. That is lining up to have a great checklist.