Your question itself suggests this to a degree, it is couched in terms of one individual's reason deciding what ancient tradition and institution is worth preserving and what is not and talking as if the proof is on these institutions rather than those who would knock them down. If you can pass such judgment surely a centralised elected legislature can.
Now you call yourself a libertarian socialist. I'm not quite sure what kind you are, I haven't seen you mention the likes of Kropotkin much so you may not be that kind but still you could gain much by reading the likes of Hayek, Nisbet, Oakeshott and Burke. You don't have to endorse any kind of rightwing traditionalism but they have a lot to say to any libertarian and decentralist. Robert Nisbet has little but priase for Kropotkin and Proudhon.