Every school-aged generation had at least one stupid thing that was the trendy, cool thing to be into, usually with with some collectible aspect designed to make your parents regret having kids. Collectible stickers and trading cards, pogs, spinning tops, Pokemon, tabletop minis... Game publishers have just lucked out that this time, it's their games and their skins.
Can't blame them for milking it dry, because just like the other trends, it's very probable that, at some point, this too will probably die.