We are generally in an anti-bureaucratic phase, and within education there is no organized, powerful force for centralization. Most politicians don't want to do the work of persuading voters that they should be taxed more in order to educate other people's children. Local school boards don't want to give up their power. Christian conservatives are afraid that centralization in the public schools will lead to liberal indoctrination. Economic conservatives want to privatize education as much as possible.
Unions resist the teacher-evaluation systems that come with centralization.
From a philosophical standpoint the main force working against centralization is a progressive, humanist, anti-utilitarian view of the purpose of education. A school should be an arena for open discourse about values, not a job-skills training center. It gives them creative latitude in the classroom and gives value to what they do. What I encountered at P.S. 114 would deeply affront the progressive sensibility in education. Success for All turns teachers into drill instructors.