Because a few years back, everyone got fed up with paper launches and spoiler launches where there was months of hype and spin before there was a product to buy or even read reviews of.
It doesn't do anyone any good when companies "sell" products, but don't have anything you can buy for months.
Look from the producer side though, if they are forced into paper or spoiler launches they are obviously not in control of the situation. This implies on average they will make less profit, and the customer will get a better deal.
As you said, the tactics used above had long term consequences "everyone got fed up" meaning they were less likely to be repeated in future by the company when the game was replayed ie the behaviour was self correcting.