I’m not dismissing the intent of your suggestion, but even though it might seem minor in-game a foot fracture is not something a normal person would be able to walk on and ignore the pain. There should be more alternatives to mitigate pain in this situation, like additional ways to create makeshift splints or making it so crawling doesn’t use the foot, but I’d be hesitant on changing the pain balance.
I would also not want to rob systems of their complexity; like any other mechanic, pain management and medical knowledge in survival situations is a learned skill. It makes sense that not everyone on the ship ICly and OOCly would be prepared for it and it gives greater weight to those who have medical training. If you’ve seen antags go down with painkillers in their system then that might very well be a bug, but there are a lot of variables at play. Worst case scenario, ahelp and staff can rejuv you if necessary. We are more than willing to help people who die to BS.