You know why this happened? Because people bought codes with stolen or otherwise compromised credit cards, listed those codes for resale from legitimate purchasers looking for a deal, and then eventually the original purchase was noticed by the stolen/compromised cardholder and the charge reversed.

Payment processors do not like this. If you make your payment processor angry with you, they drop you. I imagine SE uses a first tier processor, and if you get dropped by one of them none of the others will take you. Chargebacks happened, processors told SE to <do this thing now>, SE complied.

Square Enix didn't ruin Christmas, people stealing things ruined your give away and I really suspect Square Enix didn't have much of a choice but to comply with a request from a big payment processor.