The new Lucas Museum of Narrative Art is a Rorschach test for the value of mass culture, the future of Los Angeles and the legacy of founder George Lucas. Its arrival also happens to highlight LACMA’s epic flop of a main new exhibition hall, the David Geffen Galleries building, which debuted across town four months ago. LACMA’s failures, involving substantial public money, constitute serious lapses. Its director Michael Govan sits on the Lucas Museum’s board. Lucas’ wife, the prominent executive Mellody Hobson, who was a driving force on his project, is in turn a LACMA board member. Govan might prevail on Lucas to join as well, as an…