Can you tell me if there are any positive affects of having very high arches?

There are some:: Usually, less prone to developing extensive wear and tear in the foot joints, less know for developing a bunion deformity... Watch out for toes getting curled/ contracted ensure your shoes do not impinge on the top of the foot nerves and tendons.

High arches: As stated - less likely to have bunions , but hammertoes can be problematic. Be careful with shoes as the soft tissue structures at the top of the foot can be injured by ill fitting shoes.