Exactly Hinata could maybe be a medic, but she would be a fodder medic. She would never be as good as Sakura so no she would not have helped in the saving gaara arc.
I don't think she would be a fodder medic if Tsunade was her teacher. Having 3 years of uninterupted training under Tsunade, coupled with the byakugan an it's ability to see through solid matter, and the gentle fist style allowing Hyuga the ability to project chakra from every tenketsu in their bodies. Any Hyuga would be in a good place to become a medic if they wanted.
However Hinata's ability's are deployed for recon and detection. Hinata's byakugan has a range of 10 km/ 6 miles. She can see chakra flows, barriers, and through genjutsu. Hinata can do all that after her own training during the time skip. So in terms of application, both Sakura and Hinata have a solid place in their respective fields.