There's nothing wrong with dictatorships, but for some odd reason dictatorships of modern history have been associated with ideologues and totalitarianism. For example, Mao, Hitler, Stalin and so on were driven by a crackpot ideology, and they weren't like the generally mellow autocrats of old. Another thing modern dictatorships have been associated with is corruption. While they promise a more efficient state, they instead end up assigning position on nepotism rather than merit, and basically they just mass up enough money so they can resign and live somewhere else, lol.
Although, a lot of traditional monarchies, such as Saudi Arabia, aren't so bad. They aren't totalitarian, although they are authoritarian. Nevertheless, given their political climate, it's hard for them not to be. Another thing associated with traditional monarchies is the erosion of the monarch's power to the point where they only exercise executive power, and then later they are usually either overthrown or reduced to constitutional monarchs.
I do have a theory about this though. Usually charismatic dictatorships are tyrannical, because the charismatic dictator is usually egotistical and it was his ideology that brought him to his position. In the case of traditional monarchies, well, usually somewhere along the monarch's line the successor just doesn't give a crap or he's an idiot.
The autocracies that work, it seems, are the ones where the autocrat possesses an exceptional ability to solve problems and manage the state. As long as the autocrat merits their power in some way, it typically works out fine. But charismatic dictatorships, crony nuts, or idiot monarchs just aren't cool.
