New contest - again only for a small amount of player

[Mug]

That's not because the prizes are digital. That's simply because that's a big contest, so Square Enix could justify dedicating the legal and monetary resources (that aren't small) necessary to accomodate the legislation of every nation in every region.

Smaller, on-the-fly contest organized by local marketing teams don't justify that expense.

So in other words, it is a convenience issue.