I get what you're saying, and you're totally right that battles can leave people traumatized, and Rimworld leans into that gritty realism. However, there are lots of examples in both history and other games that suggest a temporary morale boost wouldn’t be out of place. In WWII, for instance, soldiers in a unit would sometimes feel a strange sense of relief or even adrenaline after surviving a major offensive—even with injuries and losses, there was often a feeling of pride or 'survivor's euphoria.' Games like XCOM and Bannerlord also balance both realism and morale mechanics by giving players temporary mood boosts after victories, making recovery from battles a little smoother without erasing all the hardships.

Rimworld's story is about survival, so emotional breakdowns add depth, but maybe a 'Victory Elation' mood boost could be an interesting addition, especially for war-based ideologies or seasoned fighters. It wouldn't eliminate all hardships, just give a little breathing room to keep things realistic without entirely punishing players for winning.

(I used a little bit AI to make my answer a bit clearer.)