This is terrible for people with glasses btw -- induces much more chromatic aberration than other light sources, and is very distracting and hard to ignore. At the edges of the field of view objects get very clearly separated, with the blue part usually being the most noticeable.

Not always, many are RGBW since the sole white LED consumes less power than the RGB LEDs shining together to produce white (I believe so at least) and the white color coming off the single white LED is nicer than the mixed color.