Thanks for your succinct, fascinating, and important question, Karen. Here are a few thoughts in response that occur to me.
One might think that universities would be dedicated to forming a universe of knowledge, that they would seek the unity among the many branches of knowledge. Instead, they have often become holding companies for separate disciplines and colleges each of which jealously guards its autonomy and competes for resources. University administrators may advance not so much through a unifying intellectual vision, but on their ability to manage strong departments.
Disciplinary rigor serves us well, of course. Intellectual focus has yielded incredible new knowledge. I have never studied how red shifts are calculated, but I admire and depend on the accuracy of those who have learned how to measure light. I can use the number of 13.8 billion because of the brilliance of people who have specialized in physics and astronomy. That list of disciplinary based discoveries could go on a long time.
With the time and effort it takes to master one field, there is not always much left over to be aware of - much less integrate - what is happening in other disciplines. Add that to the need to establish oneself in one's own discipline in order to get and keep a job, and we start to go down the road of the fragmentation of knowledge. Specialization becomes a value in itself and we get experts in teacups at Versailles who have no idea how to talk to specialists in Russian samovars.
Add to this the post-modernists who are prevalent in many of the liberal arts. The term suggests splitting intellectual periods into three periods: pre-moderns often with their ideas of religion, modernists who are rationalists and scientists, and post-moderns who see modernists as another attempt to gain power over others through intellectual claims. Pre-modern priests wore black robes and chanted gobbledygook; modern priests wear white lab coats and use formulas that the vast majority of people must accept on faith.
Post modernists aim at deconstructing intellectual and social bids for hegemony. Think of Robin Williams in Dead Poets Society. He begins by ripping the page out of a rationalist's analysis of a poem since that method kills the poetic experience. He breaks the role of the tweedy don and jumps up on top of a desk. The fruit of scientific, rational analysis is not only rigid thinking, it is industrial pollution, nuclear weapons, and global warming. The movie ends up with Williams taking his students out of a classroom with its straight rows of chairs and then into a cave with lit candles where passion can be freely expressed.
Post modernists often have a keen dislike for ideas about nature, which for them is rather like the old pre-modern view of essence. There is no natural reality that determines who we are as blacks or whites, men or women, and so on. We play out socially constructed, imagined roles. When those roles entail domination of one group over the other, they need to be exposed and taken apart.
Historians have often produced national histories; sometimes they have produced larger accounts based on the written record of the human past. They study documents in archives and libraries. Post modern historians deconstruct any attempt at grand narrative of the past few centuries or millennia. These grand narratives were written to prove the exceptionalism of the United States, the grandeur of the British Empire, the glory of Western Civilization - and the need for subjected peoples to acquiesce. Post modernists will have nothing to do with any of that. The most these historians will do is to write vignettes about the past. We create the past, or at least how we choose to think of it. There is no grand, over arching story that purports to give a recount of what actually happened but really just imposes imagined half-truths that barely mask domination. The post modernists end up being skeptical at best of a coherent story (even with many admitted gaps) that sees the last few thousand years as the recent past.
A grand narrative of 13.8 billion years based in large part on the natural sciences is anathema to post modern or traditional historians. They rarely entertain the idea that we can learn to read not just texts, but the stories that light, rocks, bones and blood tell us.
So disciplinary boundaries and intellectual hostility to grand narrative are two reasons why universities rarely seek a universe of knowledge.