As someone who devoted her own academic scholarship to cultural identity theory in art history, I can tell you historians are not prone to omit historical nuance. In fact, we excitedly look for it. It's these dynamics or twists in which we rest our stories. This is after all, the variety of varying perspectives of history. Identity politics doesn't generally happen at the scholarship level. True, like all scholars, we begin with a premise or a question that may seem slanted, but the goal is in the search for problems, twists, complicated dynamics in history particular to cultural identity theory.
Today, presenting historical nuances rests with the museums and their boards of directors. As cultural institutions continue to be managed by business professionals, such as development officers and public relations firms, nuance (i.e. historical facts, scholarship) risks being abandoned for the ease of the sell. (I refuse to believe an uncomplicated history line will secure large audiences, but I'm not in the business of sales). It is this brand of identity politics that that dictates the parameters of exhibitions. Rothstein does in fact mention the National Museum of American Jewish History as an example of how museums successfully present nuance. I will add El Museum del Barrio as another. These two institutions established themselves about 40 years ago, a time when "curator" meant scholar, not aggregator of information.
While Rothstein's critique seems to lay the blame on these cultural groups' desire to claim their history, the weakness of these exhibitions and others like them point instead to the fact that these stories are are not "their own stories." Instead, they are examples of branding for the business of museum identity. Forty years after cultural groups were offered the mic to tell their stories, have we returned to a place when our identity is someone else's merchandise?