I think it would be nice to be able to set an upper limit to the amount of MSP your maintenance facilities will stockpile. Instead of having to periodically check that I'm not using up minerals overproducing MSP or that I'm running low on MSP and need to restart the factories, it would be very nice to just be able to say, "make them until there are X number in the stockpile". Ideally, the factories would work to just keep the stockpiles at that level and not be a "make them until you reach that level and then stop until I tell you to start back up again." Also, I think you would want to retain the option to stop production completely during mineral shortages, etc.
I wouldn't mind a similar feature for fuel production, but I don't know if that would be as necessary since, as far as I know, sorium isn't used for anything else so using it all up for fuel wouldn't be that big of deal. It would provide a little flexibility, though, as you might want to use some of the sorium for fuel production and then send some of it to another fuel production site in order to not put all your refineries in one basket, so to speak.