When I got my first (hopefully only) root canal I asked the doctor basically this question. She said the nerve is most important when the tooth is growing and moving into place. After that it’s not nearly as important but sticks around anyway.

There have been designs for counter pressure spacesuits that keep the body under pressure from the tension built into the material of the suit. The head would be surrounded by a breathable atmosphere but the rest if the body would be in vacuum. Tests show they’d be quite effective.