I'd call it finished in practice. They might have had dreams of making alternate or more satisfying endings beyond the current, but there is an effective end.
Re planets: yeah just don't even bother. By the time they arrive, your production will have outstripped anything that gets delivered. I had a bit of fun setting up huge quantities of cheap things on nearly every planet and then racing the stream of pointless supplies around the map... but I was already making far more supplies per second than was delivered and able to be used due to storage and production caps (ignoring that I had no useful reason for increasing further, after some point you just trounce everything trivially).
It's a typical incremental game-reset finish, if that works as a non-spoilery answer. AFAIK there's only one, and no reset bonus / nothing changes after it. The full story is readable through the decrypter.
I can elaborate if you'd prefer, just figure I should try to stay safe by default :)
I just remember the last time I played, I got to some point where nothing new was happening for a good long while, so I assumed I was at the end of the content.
Re planets: yeah just don't even bother. By the time they arrive, your production will have outstripped anything that gets delivered. I had a bit of fun setting up huge quantities of cheap things on nearly every planet and then racing the stream of pointless supplies around the map... but I was already making far more supplies per second than was delivered and able to be used due to storage and production caps (ignoring that I had no useful reason for increasing further, after some point you just trounce everything trivially).