In-city patches of grass can be oases for rest, recreation and even contemplation and grass produces vast amounts of oxygen and sequesters carbon. What’s not to like?
Given the 3 minutes it takes to push a reel mower around a patch of grass and the minimum amount of other TLC it actually requires once you become familiar with the basics of turf horticulture, grass gives back in spades.
Nothing takes the place of grass, though pavement serves some of the same purposes because grass itself is just a floor, a ground plane, a placeholder for space. Once you try to substitute for grass, you start to realize that other than pavement, most plant substitutes for grass either take up space or are not actively usable like grass. Also, the simplicity of a deliberate patch is sublime and whether used actively or passively, grass can often get the job done better, cheaper and greener than many alternatives.
Of course, there are times when other plants would be better choices, especially on vast, sloping terrain, but deleting grass patios from the design and plant palette altogether is probably extreme, unnecessary and unfortunate. It’s not for everyone or everyplace, but it sure deserves another look.