It is noteworthy that, in Japan, even artists' and authors' associations oppose the stricter copyright that the TPP would impose.

This is noteworthy, but it's not crucial. It is a fundamental mistake to think that the views or interests of an artist should carry more weight in copyright issues that the views or interests of anyone else!

The purpose of copyright is to benefit the public, by influencing artists to make more works. But copyright also restricts and thus harms the public. It is up to the public to decide how much copyright price is worth paying to get more works.