Despots, old and new

[Inziladun]

I'm not quite sure what you're after here. I do see the potential for trouble, however, if you seek to draw comparisons of the perceived worst attributes of 'government' in Tolkien's Arda with actual sovereign nations in the real world.
In the interests of a books-related discussion, though, it would be helpful to have more examples from the books of some of the elements you cite, such as:

Originally Posted by Raynor

- persecution of the dissidents, stiffing of open debate, torture of "lower" races and even of the "chosen kind", if they stray from the official politic

and

Originally Posted by Raynor

- instilling fear in order to start wars

Also, you seem to single out Númenor for special examination. I really don't see much in the way of a modern parallel. The Fall of Númenor, in my opinion, had its ultimate root in the desire of the Dúnedain to obtain immortality. They wanted something they were biologically incapable of having. The reason apparently they alone as mortals were susceptible to this failing, I think, was bound to their proximity to the Undying Lands, so close they could physically see what in their eyes was Paradise. I can think of no 'real' parallel.

And you make this remark:

ruthless rulers, proclaiming "divine" guidance, while perpetrating massive acts of violence; in Ea, take Numenor towards its end; in RL, take some modern day leaders of "superpower" nations, from the Western side of the fence, and, say the Romanian Iron Legion government, or, why not, the Nazi regime itself

The rulers in Númenor who hastened the realm to its end originally did not claim to be following the will of the Divine; in fact, they had explicitly turned their backs to the Valar and Ilúvatar, and were veering toward a more secular society, eschewing the religion of their forebears.
Upon the arrival an actual 'divine' being, Sauron, they began a 'satanic' religion, and their road to ruin was all but assured. They really were 'inspired' then by what they took as their god, an 'angelic' being in incarnate form.
As far as I know, nothing of the sort has occurred in our world: incarnate Evil whispering in the ears of a king.