Its not just the bad ones. If you compare the aggregate performance of democracies versus hereditary rule then democracies have less famines, less aggressive wars, fairer justice systems and higher standards of living.
Less famines: This isn't a result of monarchy vs. democracy. Was France more prone to famine under Napoleon III than the republican governments that followed?
Less aggressive wars: Are you really going to tell me that Great Britain and the United States in ~1800 (have to start "democratic" at some date for the former, and I'm not sure where) to 1918 (or thereabouts) waged fewer aggressive wars than the leading monarchies?
Fairer justice systems and higher standards of living: Hardly inherent qualities of monarchy vs. democracy. See below.
As for your last comment, that just shows the whole problem: social policy shouldn't depend on one man's desire to permanently cling to power. Plenty of democratic leaders willingly step down. How many monarchs have?
Oh I see now. It's totally not a problem for radicals to make it so monarchs feel threatened by reform, because monarchs should have no concern for their own interests. They should gladly surrender power, because by the very nature of them being crowned heads they're unfit to hold it*.
That attitude is why you see monarchs in the 20th century disliking liberals and reformers. And quite frankly, I have a lot of trouble blaming rulers for not wanting to be made figureheads.
You could try to have the crown as an ally, using the power of the sovereign to promote and protect social reforms - but that would require not treating their elimination as the (pun intended) crowning triumph of reform/liberalism.
*
I could make a snarky comment about the ignorant masses, but I'm trying not to.