I am sure 52 mm are still the most common size, but pretty much everyone I know buy or ride 54 mm and up, with 54 to 56 mm being the most common size.
The good thing with that is there are a lot of used wheels that come back to me, when they are 50 to 52 mm in size, which are wider than the usual 52 mm sizes, which I prefer anyway.
Comparing the smaller size wheels, they definitely have a purpose, but they almost look too skinny against all these other worn down bigger and much wider wheels.