If they added them all at once, don't you think that they wouldn't have enough promo codes to give out? It's better to go a bit at a time and offer promotional discounts with new products than releasing them all at once. As a cashier at McDonald's I can attest to this business tactic. Besides, wouldn't you like to have a constant slew of promo codes crawling along so you can keep getting upgrades with discounted prices?

On topic of referrals, I haven't gotten any x3