The Director (planet selection screen) was changed just before the alpha...
The above is a photo from a page in the player guide, it shows how the Director used to look with the mission selection being around the tower.
Personally I really like this and think it works really well so not sure why it was changed! Scrolling over to the side of the screen all the time is a cumbersome UI experience.
Its interesting that a picture like this gets into the player guide which must have been produced this year, especially when its so different to the interface we ended up with.