Because there's not much to show yet gameplay wise but they know they have to advertise their game even at this early stage. At least it's not a Shitty Pixel Art Indie Game #2134.Why don't they show some more gameplay if their game is so awesome? Getting kinda tired of talking heads with the same E3 trailer being repeated over and over again.
And Hello Games ignored Angry Joe at E3 which is a huge plus.