Often, the reason is that some constituency, possibly a small one, that strongly benefits from the existing status quo, actively works against the political experiment using the judicial system; and the rest of the electorate doesn't care enough to fight them effectively to make the experiment possible.
This is actually a problem of decentralization, not of centralization. A stronger central planner would be able to just crush a small group of concerned citizens who are independently organizing to fight a political experiment that impacts them, and do that experiment anyway. This is a good thing if you expect that the political experiment is just fucking over some innocent people for no reason; and it's a bad thing if you think that the small, dedicated group of activists are actually rent-seekers in some sense who are benefiting themselves and making everyone else in society slightly and diffusely worse off.