The Dwarfs may be better at making steel, but they are also very traditional. What say a new blueprint of leonardo's or albrecht Zweistein's was uncovered for a new process to fold steel?
Especially if machinery was involved, I dare say the Dwarven tradeclans would be in uproar over something that could cost a a dwarf honest work.
Secondly, it could just be innovation. Why would dwarfs bother with fluting, flat metal has done them well for thousands of years, maybe they are just stuck in their ways.
So whilst I agree that Dwarfs are better at making things, i also don't think they are as innovative as Humans (which is why i hate the new dwarf models so much)
Why would this be restricted to just Brettonia though? After all, put enough monkeys in a room with enough typewriters.........