I think you're missing the point. Taylor Swift is not "white-washing" a particular era because she acknowledged that it was indeed a very terrible time for black people and minorities. I think it comes down to the aesthetics of an era that draw people to romanticize those time periods. I personally love the era spanning from the 1920s through the 1940s, not exactly a great time for minorities either. I love WW2, I love the movies of the 1930s and especially the 1940s, I love the literature of the era, the fashion, the automobiles.

One can romanticize an era and omit a certain horrible aspect of that era while at the same time acknowledging still the horrors of said era. One can romanticize the Medieval era because they love knights, kings, epic battles of the era, castles, and say: "I'd like it without the superstition, the Inquisition, the tyranny, and the Bubonic Plague." That does not mean that they don't acknowledge or deny those things (unless one is particularly flawed and indeed desires those things). Black people can do the same thing to. They can romanticize the Wild West, the French Revolution, the 1980s, and/or the Edwardian Era. It is customizing history of sorts but that is not a problem if one does idealize parts of history, without denying the harsh actualities of those eras.