Re: HL-20
"Strange they were planning "up to 10 astronauts". When have they ever needed that capacity?"
It's a bit of a chicken/egg problem. If they had the capability to easily carry ten people to/from orbit, then there would have been missions to make use of that. such as having ten people on the ISS at once, knowing that they'd have a way to get them all home in an emergency. (There's never more people on the ISS than there is capsules to bring them home).
Assuming the life support can keep up, having more people on a mission can help, because more people will be available at any one time, and if (eg) someone became ill, there would be someone to take over for them, rather than nixing that part of the mission.