Ask the pro-centralization person if he favors looking to the United Nations to rectify abuses perpetrated by the U.S. government. The principle is the same.
Historically, the ultimate way to free yourself from an oppressive jurisdiction is physically to leave it. Jurisdictions that are too oppressive face competition from nearby ones that give their inhabitants fewer problems. The implication of this reality is that a plethora of small jurisdictions is better for liberty than a handful of big ones.
This is a good piece dealing (in part) with the issue you have raised: http://www.lewrockwell.com/block/block48.html