Probably has something to do with licensing. I often find something that I like in another Big 10 school and they don't make Penn State version because of licensing. It seems to be more prevalent today and I wonder if the licensing lawsuit has something to do with it.
That's always my assumption when I don't see PSU merchandise but see a lot of OSU and Alabama. They can't keep the good stuff on the shelves and no one wants to buy the other stuff.