What about issues of protecting the rights of the creator?
The U.S. has become a signatory to the Berne Treaty, which has broader definitions of "moral rights" for authors and creators; also, actors, models, and performers are more affected by impersonators or cheap knock-offs these days, and are seeking more protection. Since the big publishing and media companies want to guarantee their continued dominance over the channels of distribution, there's a lot of money being argued over which means this is going to continue to be a lively legal dispute for years to come.
And since the Internet is global, differences in the length of time granted by various countries for any intellectual property protection are going to be more noticeable. (Japan, for example, only gives a 25-year copyright, which means Elvis and the Beatles are no longer fully covered!)