I bet nexon knows, so they put very few 'serious' items in boxes so people would roll a lot more trying to get those 2 specific items.
I mean that's one way of doing it but if there were more items people wanted, casual spenders (me) will start spending too. Dunno how much revenue they get from whalers trying to whale that one thing vs casuals dropping a couple 20s to try their luck. Right now it's just not worth it for me.