I suspect a large part is that the visual nature of the topic simply lends itself to endless bike shedding and fashion cycles; maturity and stability are going

I suspect a large part is that the visual nature of the topic simply lends itself to endless bike shedding and fashion cycles; maturity and stability are going to be anathemata in these contexts. But it also doesn't help that input/output formfactors keep changing. We just about understood what did and didn't work with terminals when desktop GUIs sprung up, by the time those started maturing, we had to figure out how to adapt to PDAs and pen inputs, then came smartphones and tablets, then 3D for a while, then VR, and in parallel to that increasingly exotic "classic" form factors like folding devices with fluid screen sizes, ...