The USPS has cracked down on supply misuse quite a bit. Unfortunately, it's quite difficult to imagine all the ways that unscrupulous people will be, uh, unscrupulous. I believe the underlying goal is to have everything go Priority and I believe that from a operations standpoint, boxes in a limited number of sizes and dimensions optimizes their handling and processes so it makes sense to them to offer the boxes for free. I don't want to be charged for these boxes, so I don't like that idea at all.
I use other boxes for my media packages. Parcel post is no longer a cost advantage for me after the last rate hike.
cj/