It was originally 14 years back in 1790 when publishing anything was expensive, distribution was difficult, and worldwide distribution was nearly impossible. Today you can publish works across the globe at close to the speed of light and at very little cost. 10 years seems pretty damn reasonable.

The purpose of copyright is to encourage the creation of new works and allowing people creative access to their own culture accomplishes that goal a whole lot better than protecting the profits of corporations for ~100 years.