Of all the biennials, triennials, quadrennials, internationals and massive group shows, Documenta, established in 1955 and held once every five years in Kassel, Germany, is seen as the most serious. A statement show. It can also be seen as something else. From the sweeping ambitions of its curators to its numerous large indoor and outdoor projects to the many venues across which it takes place, everything about Documenta is huge. Which makes the event, the 2012 edition of which starts June 9, an occasion to address a troubling development in the art world: bigness. Biennials have become sprawling and ubiquitous. Ditto art fairs. Galleries are vaster than they’ve ever been. But who is all this bigness good for? Is it any good at all?