A reader writes:

More than all the revolutions that you have mentioned (Velvet, Green, Berlin Wall, Tiananmen, Romanian) Iran reminds me most of one that you have so far skipped: Serbia in 2000.  There a brutal but often popular regime had manipulated a number of elections over the course of years.  The leader made a living out of bombast and blaming western democracies for oppressing his people. Eventually, he misjudged an election and made a clumsy attempt to cover it up with fraud. Fatally, he made the "mistake" of allowing peaceful demonstrations to take hold. Milosevic lasted two weeks.

Leading the populace to believe that its opinion matters is extraordinarily dangerous for a regime that has no intention of listening.