That's a very low bar. Expert computer users like you and me have no problem with a screen that has even thousands of pieces of information on it. We use contextual cues to help us navigate that space, relying on good information design. But most people find current computers overly complicated. I think one of the reasons smartphones have eclipsed PCs is that the 4 inch screen forces you to cut down to a more human scale of choice complexity.
But that's why I am finding myself agreeing with OP that conversational interfaces are the future, for the same reason. They will force us to design down even further, into a one-dimensional UI. Choice, choice, choice, choice, etc.
That UI will be a slight simplification on the current phone UIs, and of course multiple threads can be shown on the screen at once to allow better use of screen real-estate for those who need it. Essentially, you just add lots of these one-dimensional UIs to the screen and multi-task. But the capital-T Truth is that even without a screen reader, using a Desktop computer and indeed vision itself is a largely linear process. Experts get fast at it, but we still must scan about to discover new information and places to interact. I think we will be surprised how much of our computational life actually becomes conversational.
One of the most exciting things to me about conversational interfaces is that writing automation software that uses them is much more trivial than writing automation software for a big complex GUI. And building AIs that live in them is also easier.
In general, I think there is something very important in the space of UI for beginners, mobile users, AIs, and people with disabilities that is happening. A kind of crystalization of intent. I'm only hearing people like OP start to talk about it now, but I actually think this is the next big wave in UI. And I do agree with you that most time spent improving UIs is wasted in exactly the way you describe.