Here is Edward Gibbon in 1776 in 'The decline and Fall of the Roman Empire' on some of the best Roman Emperors (Marcus Aurelius among them):

The labours of these monarchs was overpaid by the immense reward that inseperably waited on their success; by the honest pride of virtue and by the exquisite delight of beholding the general happiness of which they were the authors. A just but melancholy reflection embittered, however, the noblest of human enjoyments. They must often have recollected the instability of a happiness which depended on the character of a single man. The fatal moment was perhaps approaching, when some licentious youth, or some jealous tyrant, would abuse, to the destruction, that absolute power which they had exerted for the benefit of their people.
                        
There you have it (could that man write or what!) Dictatorships can be great in the short term but are ultimatley not desirable because of the possibility of enormous power falling into the hands of one evil man.

The sooner the Americans reading this get the point and start campaigning for a constitutional monarchy the better!