Why Are Great American Figurative Artists Being Forgotten?

Why have so many fine American Artists of the past 20th century been removed from the art history books? Should alternative museums be created to house these artists/as is now being done for American comicbook artists and American illustrators. Maybe it is time to rediscover these American Greats. A revival/rediscovery similiar to what the Blues Guitarists went through in the 1960's perhaps is long overdo. The American Artists I am thinking of are the WPA Artists and those associated with them. I would like to open up this subject for discussion and comment.