The kata are like the "encyclopedia" of the arts. A scientist doesn't say "All those old formulas and axioms don't apply to me because I only work in the 'real' world of test tubes and chemical reactions." He knows that there is tremendous value in all the documentation of all the scientific research that has gone before. Traditional MA katas are just like that. They contain the documentation of what other people learned the hard way long before us. They didn't survive because the guy who created them was a weakling. They survived because he was very good and the people who followed him accepted them as his gift from history.
This is pretty obvious to me, but we live in a world where "old is useless". It's sad.