i think they did need to unify the design and branding but i also agree they went too far with it. if they had only chosen 1-2 colors for each app icon that would have helped a lot.
Most software pretty much doesn’t give a fuck about the visually impaired despite everyone talking big shit about accessibility. So I could certainly give a fuck what color someone’s logo is.
To me, that’s just the case for camera and calendar. Maps is IMHO perfect (except the unnecessary G) and the red-and-white envelope is quite well-known.
I think what really bothers me about the aesthetics is that the shapes are broken up by the coloration. For example, the pin icon for Google Maps looks almost like a hook, because the yellow has little contrast on this white background.