I'm not defending common core so much as tired of everyone finding every 'argument' under the sun to throw at it. As for national control, there's an argument that can be made that basically says it's necessary in order to meet national standards, and that standardized programs ensure that students get similar education (especially helpful if a student moves at some point during their time in education), but I don't pretend to be an expert. Drawbacks, of course, include too much testing and teaching to tests, etc.
to paraphrase Churchill, who said "It has been said that democracy is the worst form of government except all the others that have been tried," Common core is the worst form of education except for all of the other forms we have had in the past. People, myself included, have lamented the loss of shop, home ec, arts courses, etc in the common school curriculum, but with the level of expectations we have for high school seniors (both in breadth of scope and in degree of specificity in topics), it's crazy to think that going back to 50's era school set ups would serve the students. Now, there are a million and a half threads to this topic, including "why do I need a 4 year diploma to be a secretary?" and "should we specialize kids earlier in life, or does that seal their future?" and "what defines a 'broad spectrum of education?", so making sweeping statements like the one i did in the previous paragraph is obviously going to be problematic and come with a lot of caveats. The problem is that we have millions of high school kids in North America, all using this same system (generally). If we move to something else, it's going to be like diverting the Alpheus, so people are hesitant to try new things.
A necessary evil, really. My sister is in IB right now and I'd argue it's made her more reflective and a critical thinker. But it's also made her woefully under-prepared for some parts of her ACT/SAT testing. IB is an international program so it's not as focused on the standardized testing of the US - standardized testing that's letting her gun for Stanford.