First: Many would agree with Aeschylus' comment in his play, Agamemnon that Clytemnestra addresses to the captive Cassandra:
An upstart lord,For the same reason, the play shows the people of Mycenae alarmed when Clytemnestra and her lover usurp the throne.
To whom wealth's harvest came beyond his hope,
Is as a lion to his slaves
Second: Anyone prepared to resort to nefarious means to seize power even once, let alone three times, shows the sort of alarming lust for power that makes most people believe he is the last person who can be trusted with it.
Third: When a leader has no claim to hereditary or institutional legitimacy, all that really leaves him to rely on is force.
And, it must be added, no all the tyrannoi who were Pisistratus' contemporaries were as benign as he was. Many were tyrants in any sense of the word. But after reading about his seizure of power, it is hard not to come away with the impression that, after all, a leader with no institutional claims to legitimacy, whose frail grip on power depends entirely on being popular, might not be an altogether bad thing. There are three main reasons usually advanced why a dictator whose power rests entirely on popularity is bad:
First: What is popular is not always moral. See Hitler, who was actually quite popular until he ran into trouble in the war. Or George Wallace: "I tried to talk about good roads and good schools and all these things that have been part of my career, and nobody listened. And then I began talking about niggers, and they stomped the floor." Still, most of the time the nastier forms of scapegoating are what a dictator does to deflect anger when his popularity is slipping anyhow. There is no evidence that Pisistratus resorted to such measures.
Second: Sometimes unpopular actions are necessary. Unpopular actions may, indeed, be necessary. But nowhere near as often as most people think. Of course, in saying this, I, like most people, am a product of my times. And in my times, from the 1980's to the present, international creditors tend to assume that the more unpopular a measure, the more virtuous, and the more suffering they can inflict on an economy, the more they are proving good management. And we may be about to see a rebellion against such thinking. (And Greece may lead the revolt!) But what about war? Pericles is cited as a fine example of a leader with true democratic legitimacy persuading his countrymen to take an unpopular action -- withdraw within the city walls and allow the countryside to be pillaged. The wisdom of this action is questionable (it led to a terrible plague), but even granting that it was the wisest way to fight the war, it would have been infinitely better not to start a stupid, senseless war in the first place! The classic modern example is Winston Churchill, offering only tears and toil, sweat and blood. Churchill provided outstanding wartime leadership. But before the war, he inflicted a decade (or more) of senseless suffering on his countrymen by returning to the gold standard at too high a rate. No wonder the people dumped him as soon as the war was over!
Third: Popularity is fleeting. No matter how able the dictator, sooner or later his popularity will end. A king will remain legitimate despite is waning popularity. A democratic leader who ceases to be popular can be removed without resorting to violence. But if a dictator rests his power entirely on being popular and sees his popularity end, then he truly does have nothing left but brute force. Pisistratus' popularity never failed throughout his lifetime. But all leaders are mortal, and when he died, his sons took his place.