Tiling window managers predate Linux (and Mac and Windows). Not to diminish the work people are doing to make the desktop better, in general I think on the Linux side things have gotten pretty good, but it's hard to come up with very many widely used substantial UX changes. Comparing to say Windows or Mac drawing an arbitrary line at 1990, networked hypertext, desktop search... What else? The infrastructure underneath is all way more advanced but the overall experience is pretty similar.