Unable to keep purchased skin sets

If I buy a Snowfallen Character set, I'm forced to open it. - However, it has the functionality for being stored in the inventory, as people have glitched it with commands before (but they weren't openable due to being unverified or something)

Why can't I buy these & keep them in the treasury/inventory? - This also applied to Forge, really sucked as I wanted to collect all 14 chest types (12 characters, 1 all characters, 1 pugna)