Pretty sure they already do it. I've also noticed that if you have a fast connection (like 1 Gb/s down), it might be faster to download the game when it release

Pretty sure they already do it. I've also noticed that if you have a fast connection (like 1 Gb/s down), it might be faster to download the game when it releases than it is to preload it and then decrypt it, since the decryption process is quite slow.