As master swordmaker Korehira Watanabe said in the above Esty documentary, the katana can express the soul and the beauty of the Japanese people. Watanabe is one of only thirty master sword masters left in the country.
The tradition fell by the wayside over through the ages. There are many reasons for this: the Meiji government's decision to outlaw the samurai from carrying katana in the 19th century, only permitting the military and the police to carry them. Or simply that, over time, the formulas for making certain types of swords were lost to the sands of time.
Japan is a country rich in tradition. Yet, many of those traditions seem fuddy-duddy and only passively interesting to modern Japanese. Many young Japanese women can't even tie kimonos themselves, and must go to a kimono fitter and pay someone to help them put it on.
Swords are very much a part of popular culture in Japan, appearing in movies, manga, and video games. Yet, the act of making them and the swords themselves simply do not exist in daily life.
There's an unrelenting determination needed to craft the perfect katana. Watanabe has spent the past forty years making swords, and it's only within the past five that he's been able to recreate something that resembles an ancient blade.
Most things can be mass produced, designed on a computer, and sold in identical shops everywhere. Some things, some very special things, need to be pounded out with a hammer in a shed in Hokkaido.
Today, hand-made swords are not considered weapons, but art, and the necessary paperwork is required to own and display them.