"copyrights hinder innovation by game designers seeking to build upon such games, and shortening copyright would breathe new life into games who have long since passed into obsolescence."
It's a good argument, but a crappy example. Nintendo's not a great company to point to here, because they tend to release and re-release anything popular they've made. Mario Bros, I know, is available on the Wii and Wii U at least via the Wii shop (maybe also on the Wii U's virtual console). It's also been re-released in several incarnations before that. It's still pretty popular for a game of its age.
Why not point to the forgotten gems? I just heard that there was to be a remake of Day of the Tentacle, that was canned. I wasn't even aware such a thing was in the works until it was gone.