But the story is what makes the goals interesting!No story.
Not "Automate green science because that's what we think you should learn next."
But "You need to construct a train to retrieve goods from the spaceship across the ravine, because XYZ." Or whatever.
And of course to construct a train you need to automate green science, but that's what the player has the pleasure of figuring out for him/herself. The story presents the problem, and the player invents the solution, and thus learns the game mechanics.
I've said this before, but my favorite level in the original campaign was the one where you get to the wrecked base and discover everyone's dead, and you need to bring all the systems back online. I played it quite a few times, because I kept improving my understanding of how the various systems interacted and how to best arrange the smelting, or the railroad tracks, or other things. I'd love to see more levels like that.
I wonder why the campaign is viewed as just a tutorial in the first place. Why can't it be an end in itself, instead of a stepping stone to free play?