public art and the tilted arc

Q1: One of the stipulations of site specific art is that there is usually seating, it provides shade, or other physical accommodations, but if this is what characterizes site specific art, then why is Walter DeMaria's Lightening Fields considered site specific art? It lacks the same things that the Tilted Arc lacks - seating, shading, etc - yet it is looked at and appreciated as site specific art. how is that possible? 

Q2: One of the main controversies with the Tilted Arc is that the local community had no involvement in the decision making process. This accusation seems inadequate because why should an artist, who makes sculptures and other artworks for a living, need the approval of a community? It just seems to me that GSA and the NEA did not appreciate Serra's work, and convinced the community that they were unhappy with it as well. Any other ideas?