My screen doesn't have a notch, so I can't be bothered to think of any
But, seriously, "glass half full" is that it's not a notch cut out of your screen but two 'ears' tacked on
in addition to a 16:10 screen. At least in fullscreen mode (when the menu bar is hidden anyway) it's supposed to be available to compatible apps. It could be used for a status display, or for the score in a game. A music/video editing program could put the timecode on one side, and the master volume control on the other.
...but that means new widgets designed to fit in the 'ears' - they are
not going to show up on Airs, entry-level MBPs, iMacs or Apple's external screens, it's less likely that software designers will bother.
What it's *not* so good for is holding the menu bar - which was never designed to fit into ears (the clue is in 'menu bar'
singular) and has an 'auto hide' option (default in full-screen mode) if you wanted the space back... and part of the
point of full-screen mode is hiding everything not relevant to the current application (like the right-hand part of the menu bar).