There are certain appealing aspects to having national standards, such as looking at a country like Singapore or Japan that has very high standards and achieves great things through them. However, within the United States, we have already seen tendencies from those in power to dictate down to the local level things that are “best” for us when in fact they’ve been proven wrong over and over again. This article by Laurie Rogers is an excellent summary of some of the issues.
http://ednews.org/articles/national-standards-national-curriculum-dangerous.html
You are in fact correct that standards can work both ways. Ontario is a prime example of jumping on the American constructivist math. The gov just dumbs down the test to make it look like the marks are improving and even uses rubrics for their math tests(formulae sheets given as an aide). The curriculum has been hijacked by the social pychologists who gave us reform math, using their propaganda as leverage. Success for all, is one of their favourites here. We have curriculum in math and science that has the word discuss the social impact of etc. No real mathmetician would approve of this curriculum, things are out of sequence and it is baby math. The texts are now standardized to have the students write stories about math in grade 7.
The real soln to the problem is to let math/science & tech decide what is math/science and tech not outsiders be it faculty of ed socio pyschologists nor government monoliths.
a good discription of some of what is happening in Ontario can be found here
http://www.magazine.utoronto.ca/cover-story/fear-of-numbers-math-tutoring-cynthia-macdonald/#comments