I think I might not be explaining missions well enough. Missions are things that you decide to try to do with at least one crew member. Planning a big lavish wedding was just an example off the top of my head, but it's not that odd: it'd be one or two crewmembers (maybe the two people getting married) spending time planning their wedding, and then throwing it.
The mission framework is extremely straightforward and you know right from the start what you'll have to do to accomplish the mission. Some might have time limits, but the vast majority do not: you want to accomplish them fast because you're burning resources. Because you know everything about the mission before you accept it, experienced players can easily plan ahead and handle a more complicated workload. Beginners will probably micromanage day to day life to try and eke out more points, and that's fine, too.
The outcome of a mission is only variable when it's competitive, which I didn't go into during the video. In a competitive mission, both sides are working towards the same point cap - but as each side gets more points, the difficulty for the other side decreases. In the end, whoever reaches the point cap first "wins", and the difference in points is the amount of the win.
This is easy to do, because the outcome of missions is always very simple. Money or political favor for the player, economic, industrial, political points for a faction. Sometimes a character or planet will change factions. Your personal crew missions are a bit more variable, of course, but it's still mostly just points. It shouldn't be dull: everything in a game is mostly about points, it's just a matter of how it feels to earn them and what their value is.
Sometimes you'll have to choose between mission A or B, but once chosen, the missions probably won't change at all. This should feel pretty solid, because the choice comes up during an explanation of the outcome of the mission, and it should feel like a reward or a raising of the stakes.
In the end, there may be something like "plots" - long-term goals and mission chains that pop up over and over. For example, raising a nation's economic strength, or creating peace between warring states, or journeying to the center of the galaxy, who knows. But that's a longgggg way off. Even without that kind of structure, players will probably create their own long-term goals and choose missions that further it.