Nude pumps are best worn with outfits where a grounding color is not needed for the shoes. For example, when Megan Markle wore a hunter green blouse and leather skirt, nude pumps were the absolute right choice, especially as day wear.
If she had worn a red ensemble, the nude pump would have worked, too. However, recently, a photo of a colleague at an evening event revealed a navy dress with a nude pump that looked lost. A black or dark navy pump would have enhanced the dress. Wearing the nude pump made it look like a day outfit. A nude pump with slacks works best in the same color family.