If anything I suspect a galactic collision would be a driver of increased star formation, and thus a catalyst for galactic recycling and chemical evolution with

If anything I suspect a galactic collision would be a driver of increased star formation, and thus a catalyst for galactic recycling and chemical evolution within that Galaxy. It could even be something that leads to higher rates of biological evolution. And like you said, the distance between the stars is what prevents this from being a total catastrophe.