Everyone does have equal rights to roll on the card, whether it's only worth 50 MGP or not. This shouldn't be the issue here.

The bigger problem is that this was a change that ultimately benefits no one in the end. If there were issues with people actually obtaining the card before, then adding the card to the loot list just promotes the idea that the card is even rarer. It puts a distaste in everyone's mouth, dangling a carrot in front of everyone... which isn't entirely welcome when the card is nowhere near as effective as the Onion Knight's card.