Philip Kennicott: “A simple dismissal of their right to be heard will render any subsequent decision in the case illegitimate in the eyes of many Washingtonians, including much of the local arts community. Artists are essential to the cultural and economic vitality of the District, and they are arguing, in clear and compelling terms, that tearing up William Corcoran’s deed is bad for the sector they represent. And that’s bad for all of us.”