> Why care about OS:es when there is no room for anyone on that level of abstraction apart from a handful developers at MS, Apple and Google?

There is as much room as there are people frustrated with the "state of the art."

Edit: Have you seen this apple commercial https://www.youtube.com/watch?v=OYecfV3ubP8. Yes it is from 1984 and you might think it doesn't apply.