The only odd thing is the lack of black. Black, white, silver/gray have been the vast majority (75%+) of new car sales for over a decade.
To some extent, the proliferation of metallic and pearlescent paint variations may mean that these colors are less boring than the old flat white and such. I generally didn't like white vehicles that aren't sports cars with more interesting shapes, but I'm good with the white tri-coat on my CX-5. However, I bought it used, and it had the right blend of options, condition, same price, with color being of lesser importance.
The explanation I always hear is that's what the dealers want. Anecdotally, VW GTIs in Cornflower Blue like mine seem to go for a slight premium, but 75-80% of them are still made in the boring colors.