I've heard from people in video stores that the cases to which you're referring were were cheaper to produce.  I have no idea if this is true, but I do know I don't like those cases, and am glad they stopped making them.  They weather more easily, and don't fit on the shelf with other dvds.  For an OCD person (lol), it's annoying.
Even the newer dvd cases now are poor quality.  Notice there are holes in the plastic behind the artwork, whereas years ago, the cases were much more solid.  It's all about money.