IRA, Hizbollah and Hamas are all nationalistic organisations in countries that are under intense external pressure, either politically, militarily or economically, to such an extent that the general population are suffering. The same was true of Germany in the 1930's. While I agree with the points you make I feel that most discussions on this topic miss the most important point of all. Yes democracy can throw up some problem leaders, but ignoring the circumstances that lead up to each of these cases is failing to learn lessons from history. While it is possible that removing the treaty of Versailles may not have prevented the nazis' rise to power, it seems almost certain that Hamas would never have been elected without the Israeli blockade and attacks. It also seems hard to imagine the IRA getting any power in a world where Ireland was not subject to brutal repression for a couple of centuries.
Democracy is not the problem, it is imperialism that is the problem. Desperate people act desperately, and voting is no exception.