In the opening of New Hope, Vader says he has dissolved the imperial senate and given direct control to the planetary governors. This technically makes planets freer than they were under the republic. As long as they give Vader what he wants, and don't harbor rebels, he doesn't care what they do or what measurement systems they use internally.
The rebels were all against the empire, but they weren't really FOR much of anything as a whole. They certainly weren't about bringing order to the galaxy by imposing a universal law of measurement. So the whole analogy breaks down in that respect.