I agree, it was never intended to be a working user interface. It was more artistic visual than workable design and that's all it needed to be. It excelled at that.
Besides, when it was created in the mid-'80s, what real-life GUI existed as a basis for comparison?
And the gibberish that appears meaningless wasn't really meant to be read on-screen, it was background detail. If meaning must be sought, I'd attribute it to some LCARS specifics that is meaningful to users aboard starships but not to our familiar 21st century systems. We've got some systems only a few decades old today that would appear unrecognizable to many current users. So what's a couple centuries from now? I imagine even "computers" as we understand them today may be so far removed from today's tech as to be completely different altogether.
But back on topic... that some have configured LCARS into a workable design today is fantastic. I love it.