For me it is all subjective, for what a sword of 1300 is better of a sword of 1800? Sugata, jigane, hamon, hataraki? But all of these things are subjective. Compare a swordsmith of different period is not the right thing, Fujishiro rating for example is a valutation of swordsmith of the same period and the same school. Old sword maybe are interesting for the historycal period, but someone can prefer newest sword like gendaito or shinsakuto, why give the title of a national living treasure to some swordsmith if their works are not so good? I think everyone must find his own golden age.