The thing about Vitality/Wounds is that it doesn't work super well to port directly into D&D. Star Wars d20 made a lot of additional changes that impacted the Vit/Wounds system, including:
- Crits were a range with damage straight to Wounds rather than bonus/extra damage.
- In addition, this was back in d20 where crits had to be confirmed, making them relatively rarer
- Armor was also completely changed, providing damage resistance rather than AC.
- Defense was now a class feature that went up with level
You could theoretically do one or more of these without using
all of them but they really worked out for the best in tandem with each other.