My point is rather than we must construct the level of government suitable to the material at hand. In order to have something as sophisticated as a Republic it is necessary to have capable citizens to fill its roles who understand why they owe fealty to it. No rabble we.
Important too, in the consideration of political systems, is the impression of history and the social patterns absorbed by members of the polity. Some of the other systems of Liberal Democracies may be more appropriate and still achieve the aim.
A good society is the goal, not the realisation of an ideological system. A good society may be facilitated in being realised by enlightened ideas but its purpose is the good and, I would think necessarily from that, the free development of its citizens.
That means having a civil society that provides knowledge, education and avenues for participating in civic life. It should be meritocratic if it is to create the performance levels necessary to maintain and advance it. And it should be a society of the rule of law where law is feasible, just and equally applied.
That does not preclude a moral component, indeed this is an indispensable part of it. Moral behaviour both fulfils the nature of a healthy people and is the path to sustainability over time.
And moral behaviour is not a capricious occurence dependant upon the pretensions of a time - rather it is something elemental that is recognisable and congruent over ages of time. It is a foolish and vain person who dismisses sedimentary wisdom or the sentiments and experiences of our forebears.
There is a law of decomposition in human organisation and the separation of the powers of government is a hedge and remedy to it. Often roles are sought to be compounded because of a failure of performance and this is often the drive behind it - to conceal an insufficiency or indolence for the task and try to maintain one's role by cheating through concealment. Controlling the function of evaluation and oversight is the strategum for this.
That necessity is the mother of invention is no empty truism and a separation of powers channels that necessity into its most beneficial form. Limited government is the best form of government, one that respects the dignity and efficacy of its citizens. Look at Venezuela for an example of a utopian authoritarian scheme that foundered on the rock of idealistic incompetency.
If you wish to make society more to your liking then first learn how to. We had a renaissance before our revolution. That is how it is done.