Since the survival rolls rarely get easier as one continues in service there must be some sort of stigma attached to service, this should apply even without considering mandatory service.
Interesting.
Not sure how you attach a stigma to hard survival. Can you elaborate?
It's not the hard survival rolls themselves that indicates this, it is the fact that they do not get easier. A skilled person is more valuable to the managers of a job than someone who has no experience. In Traveller a 20 year veteran is put into situations as dangerous as a rookie fresh out of boot camp, his experience and skill are not valued by his managers. There is no bonus to survival for rank either, a colonel is put into as dangerous an environment as a brand new army draftee. Space may be dangerous, but without some reason an organization has steps to minimize those risks for senior NCOs and officers in command who cannot be replaced easily. The IISS (scouts) can justify this (see later) but a military/naval organization has a command structure which has to be protected (if space is really, really dangerous then navy Commanders would have ratings following them around with a spare towel because having an rating do this costs less than losing a Commander).
It could be that the ranks are meaningless and the service folks have no real authority and make no real decisions. Merchant "Captain" Jameson really just passes on orders from the in a safe position real commander (maybe a computer even) which makes all the real decisions and if he dies then "First-Officer" Jane Doe can easily step in to replace him. If this were the case and the rank system is a joke without any actual authority then there would certainly be a stigma attached to anyone who continued to reenlist in a system which only had social promotions instead of entering the real world.
Alternatively there could be a social convention which prizes the egalitarianism of risk (US Marine Corp has a mild form of this convention), in which it felt that all persons should share the risk equally. The IISS of book 6 avoided the lack of ranks by adopting a non-hierarchical command structure where ability determined who gave orders BUT in book 6 survival rolls did become easier as scouts gained skills which limits how far the IISS model can stretch to explain the early universe. While there may be respect for the force-commander who is willing to subject herself to the same risks as her troops, society will still look askance at someone who is part of an organization so tied to an abstract ideal that it will sacrifice effectiveness to maintain that ideal (we might respect the Amish for holding to their beliefs at personal cost but there is still something wrong with them).
Now I have to backpedal on the stigma. Given the deadliness of the universe in general, the idea of "Egalitarian Risk" could be a universal one throughout a society. It would be an interesting society, where there would be social stigma attached to 'cowards' who weren't willing to risk their lives. Hmm, duels would probably be common which would help justify the fatality rate without creating a permanent state of war and safety devices like helmets and seat-belts would be only for cowards. It would probably lose wars with a society which believed that the best place for a general was in a bunker directing the troops instead of on the front lines getting shot at, although maybe the "cowards" would be the real commanders of the first explanation. The "cowards" could be off the tables because no player could be one and would be despised servants to the nominal officers and plan strategies which they suggest to the nominal officers. Hmm, an interesting idea/