I think Gnome has been taking that approach going back years in part because of the opposite criticism: many people attack Linux UI as being a hodge-podge with

I think Gnome has been taking that approach going back years in part because of the opposite criticism: many people attack Linux UI as being a hodge-podge with no coherent design, comparing it unfavorably to a unified UI system like OSX's, which has a coherent and integrated take on windowing/libraries/widgets/etc. One of Gnome's goals was to fix that. They might unsuccessful at doing so, but attempting a unified/integrated UI was/is a core project goal, so I'm not surprised that they'd have no shyness about integrating components that Unix has traditionally kept separate. The tiling window manager scene (which I prefer myself) is perhaps the polar opposite (some wms don't even integrate the status bar into the wm), but isn't really targeting Gnome's target audience either.