As someone who is looking to philosophy for understanding, rather than 'wisdom', my approach might be a little different to yours.
I really do not look to philosophy for wisdom. I agree with Socrates’ “human wisdom”, that is, knowledge of our ignorance. For me it is more a matter of learning about different ways of thinking about and seeing things.
You mention two philosophers who have contempt for most of us, think 'You can't handle the truth!', aren't as clever or mature as them, and so we can't be treated like grown ups, clarity is dangerous.
I don’t think they have contempt for us. I think it is that they are concerned with the problem of nihilism and ‘misologic’. I also think it fair to say that most of those who embrace these ideas do not fair well. They are also concerned with the opposite option - no one can say what is true so I can believe whatever I want to be true. Having said this, they are, undeniably, elitist. But elitism comes in various forms and flavors. As I see it, it is not a matter of regarding others as lower in order to elevate yourself, but of elevating yourself by creating an image of a higher self which you strive to attain. What Nietzsche calls self overcoming.
What is hidden from what Nietzsche calls “idle readers” is right there in the texts to be found. It is not that clarity is dangerous but rather that it is expected of the reader to able to clarify it. When this is done what may at first appear to lack clarity is remarkably clear.
'Great Philosophers' should be left to do what they want.
This is actually the other side of hiding, hiding oneself to avoid censorship and death.
Socrates was put to death for atheism and corrupting the youth. In the Republic justice is defined as “minding your own business”. This is Plato’s serious humor at play. In Plato’s imagined city (a city in speech), the philosophers rule in order for the city to be just, which means, in part, so that the philosophers are left to do what they want.
Modern thinks such as Bacon, Descartes, and Spinoza knew the risks of speaking openly and truthfully. Bacon’s essay "On Simulation and Dissimulation" is about the wisdom of “hiding and veiling of a man’s self”. Descartes chose to have inscribed on his tombstone Ovid’s motto: “He who lived well hid well”. Spinoza’s signet said “caution”.
The hard won battle for freedom of speech certainly has led to an openness that was not enjoyed in the past, but even if one is free to speak openly and honestly, we should not assume a great or even good philosopher living today will necessarily do so. Are there still truths that should be hidden? I cannot think of any that would be necessary in order to protect others, but given the polarization of opinion today it might still be necessary in order to preempt being dismissed by one side or the other.