There were recently a discussion about NASA insisting in loading propellants when crew is already onboard, and opponents pointing out that it increases the dura

There were recently a discussion about NASA insisting in loading propellants when crew is already onboard, and opponents pointing out that it increases the duration of crew sitting in the capsule during a dangerous process of fueling. It could be a lot of consideration, but if some important area is overlooked, then it's no guarantee safety will improve over some threshold. Similarly in Russian Soyuz-2 rocket the 2.1b variant adds about 10% of payload - but uses a much more stressed engine on the upper stage. That's the reason Russians don't want to use that variant for manned flights - even though there were lots of flights and rockets with engines like that certified for manned flights.