I've tried to think up some ways to increase the significance of critical injuries, as well as, raise the attractiveness of actually having a good Doctor in the group. Not just someone with a high Intellect or Medicine skill, but a Doctor. Bacta Specialist is a good segue for that I think. The book contradicts itself on healing Criticals per week as I recall, but I like only one check a week.
Some of the ideas I had, some of which are harsher than others I realize, but again, it's about both encouraging the inclusion of a Doctor and rewarding xp expenditure on the Skills and Talents.
-Only easy Difficulty Criticals can have an attempt made to heal them in the field. All others require appropriate facilities for treatment, med bay, hospital, etc.
-Each Critical injury upgrades the Difficulty of all Medicine checks.
-Critical injuries must be healed in a descending order of severity, so if you have a Hard Critical injury and an Easy, you can't even try to heal the Easy in the field since you can't treat the Hard.
-Bacta Specialist - For every rank of Bacta Specialist one additional Critical Heal check can made per week, as well as, each rank Downgrades the Difficulty of Heal checks.
Just ideas I have been thinking about.