Those in the YU world will point to the Rav and R’ Ahron Lichtenstein as comparable role models, which is true, but these figures are also a generation or two removed from the present. So different people, same question – What caused this sea change? I don’t think these people were aberrations, completely outside the norm. Their abilities were/are surely exceptional, but that is a different in kamus, not eichus. I remember someone telling me that he once had the privlilge in Eretz Yisrael of giving a ride to a gadol of the previous dor and he was amazed when his passenger began to recite poety of Bialik b'al peh from the back seat. Today, you have stories about gedolim who (as I saw mentioned in a book I thumbed through at the seforim store) don’t even know what a food processor is, and this is held up as an example to admire and emulate. It’s not that ignorance is accepted because we can’t do better – it’s that ignorance has become an ideal because we don’t want to do better.
My wife thinks that things are as they are as a reaction to the Holocaust, which created a distrust of outside culture in any form that lingers to this day. Western thought has proven itself a poor moral bulwark against the forces of evil, and so we have withdrawn inward. Perhaps such withdrawal was necessary, as we struggled to rebuild what was lost. If you would like to put a positive spin on it, perhaps the rise of the State of Israel has inspired renewed interest in uniquely Jewish poetry, writing, and culture, to the exclusion of outside ideas. My own thought is that the Chassidic movement has had an enormous post-war influence that has reshaped our expectations. Talmidei chachamim these days are expected to be like Rebbes, not intellectuals. People want brachos and segulos, not to be challenged with Kant.
All this is armchair speculation. Bottom line is that the memory of what once was is fading and is being replaced by a less enlightened and less interesting world.