it just isn't very good. Base building exists, and the idea of having your own trade network on across different planets is cool, but again, it just isn't good. Good ideas to set it apart from the others, but just not very entertaining and poorly executed. Outside of that, there just isn't much to do in the game, and nothing to bring you back after the end credits.
It's crazy that anyone who had anything to do with this game thought it would have a 10 year life span. It was purely marketing. Like you said, we'll see with expansions, but as of right now, no way.