Per your comparisons, I don’t think Plato is as eager as Nietzsche or Kierkegaard (or perhaps MT) to separate men into two groups and condemn the ignorant masses. Plato’s myth of the cave is more about PROCESS than about passing judgment on the ignorant. It’s sort of like a rational correlative to the Buddhist process of enlightenment. We ALL resist the truth when it first dazzles us and we’re used to shadows. Plato’s myth is about the process we ALL have to go through if we want to achieve enlightenment. And yes, some are not strong enough, some have to turn back. But for Plato I think all rational beings have the capacity if they can find the fortitude. And he quite explicitly says that the enlightened ones should go back and help those who are still in the cave. In this sense he’s more Buddhist and less condescending than Nietzsche and Kierkegaard (especially Nietzsche in my estimation). In this process-orientation, Plato is actually not far from Aristotle’s notion of entelechy, where all things strive unconsciously toward their ideal destination, like the acorn strives toward becoming the oak. In fact, the wedge between Plato and Aristotle is somewhat forced. They have different emphases, yes, but they share a lot of fundamentals. Aristotle learned his Plato well.
In metaphysics, I think your resistance to Plato is a resistance to a straw man version of Plato – as if his formal world is like the Christian God with the beard who sits somewhere in physical space. I find it hard to believe Plato would be so naïve. He is just saying, in the cave and elsewhere, that there is an intellectual reality, a kind of Jungian collective unconscious, which is a hidden prerequisite to all the contingent truths we find in our everyday (transitory) reality. Whether we realize it or not (and most of us don’t), the contingent truths we structure our daily lives by would not be intelligible were they not undergirded by that collective unconsciousness, that conceptual substrate of deeper truths. And the deeper we dig, the closer we get to eternal truths and the more deeply we understand the prerequisites of our surface knowledge.
So you’re right that your idea of a perfect car may not match my idea of a perfect car, but were it not for some abstract concept of perfection implicitly acknowledged by both of us, neither of us could have ANY idea of a perfect car. The concept of perfection is a presupposed premise of your idea and my idea. So now we can talk about a concept of perfection that, albeit abstract, is a necessary prerequisite to our contingent and various concrete ideas. Now we can ponder things at a deeper level, and delve dialectically deeper into the roots of our own consciousness. That’s what Plato is all about.
Re politics, of course Plato’s politics does sort men, but the sorting is not as damning as in Nietzsche. He just says that few men will find their way out of the cave and stay out, and those should be our leaders. And he is undemocratic in the sense that he seems to believe that order requires hierarchy – a practical consideration more than an existential judgment about master and slave races a la Nietzsche. We moderns tend to dismiss hierarchy as a prerequisite to political order, but go back just to the late 18th-century Enlightenment and you will still find strong and intelligent voices (e.g., Edmund Burke, Samuel Johnson) arguing that without hierarchy is chaos. So I don’t agree with Plato here, but I’ll give him a pass on politics. (From what I hear, Rebecca Newberger Goldstein’s new book, Plato at the Googleplex, presses Plato harder on the human implications of his politics, but I haven’t had a chance to read it yet.) Anyway, as I’ve said, I don’t think politics is the most compelling branch of his philosophy, but I still agree with Bertrand Russell’s mentor, Alfred North Whitehead, that “Western philosophy is a series of footnotes to Plato.”
And with due respect to Nietzsche’s wit, I think Plato would be the more amiable drinking companion.