It is NOT the job of the federal government to dictate how teacher education programs are run. Note Duncan isn't about to go after law schools or medical schools--only colleges of education in the attempt to abolish them in order to limit educational access for the masses.
When you believe education is only for job training and not for preparing an educated citizenry, then education is in fact a waste of money since few jobs require much in the way of education. Therefore you don't need highly trained teachers. That is the neoliberal mindset, and it is killing this country and countries all over the world. What the neolibs want is basically a slave caste while only the rich will have any access to higher education at all. Higher education meaning high school.
THAT is what is behind the proposed colleges of education.
Duncan and Obama need to be impeached, but it would never happen.