Many of these downloading services are to allow people to experience the game as fast as possible, not to save drive space. EQ2, WoW, TOR and others use this to catch potential customers at the spur of the moment. If someone is watching a Twitch stream and says, "That looks cool" but has to wait four to fourteen hours for the download to finish, the opportunity is lost. They are off to bed, or the next day and at work--with a good chance of not being interested. That's even if they let it download as most will just hit that cancel button when they see their weekend will be over before they can play.