There are two big problems with this idea. The first is that dials are the remains of biological organisms limited to a relatively limited environment, the white sea. Should some government attempt to use dials at the level you describe, they would go extinct like the two most powerful dials we've seen, the jet and the reject.
Secondly, dials don't really work as power sources but rather as batteries and transformers. A wind dial needs to be charged by letting it absorb wind and can only blow air out for as long as it was charged. Impact dials absorb blows than release a similar magnitude back out. While some (mostly extinct) dials greatly magnify the stored energy, none create it from nothing.
I believe Oda put these limitations on the dials to make them NOT appear magical and show why they haven't been used on the scale you describe.
Unless of course, the extinction of the jet dial DOES have something to do with the lost century.