I have worked in jobs where you had to where all white, where you could where whatever color(design) uniform you wanted and jobs where the dresscode was inbetween. The white gets dirty too easy and some of the newer uniforms, in my opinion, are not all that professional. Most of the patients and residents I have taken care say that they enjoy they cheerful designs and colours, nut at the same time like a slight difference in the uniforms between the nurses and the nursing assistants. Straight white is just too boring, and not that uplifting for the patients.
In my own personal opinion the flannel scrubs look like PJ's and BLACK, while most my street clothes are black it is not an appropriate colour to wear in this profession.