well whats the use of calling it the most massive non-nuclear bomb? Why have all that mass if the destruction doesn't match?
It's a "Massive Ordnance Penetrator" used for busting bunkers.
From the Air Force official sight.
Massive Ordnance Penetrator
Published November 18, 2011
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Mission:
The Massive Ordnance Penetrator (MOP) is a weapon system designed to accomplish a difficult, complicated mission of reaching and destroying our adversaries' weapons of mass destruction located in well protected facilities. It is more powerful than its predecessor, the BLU-109.
Background:
Flight tests have been successfully conducted at White Sands Missile Range, New Mexico. MOP integration activities for initial weapon delivery are also complete. The Air Force is managing and funding the program at this time, with Defense Threat Reduction Agency (DTRA) providing support.
Early tests of MOP were conducted by DTRA under the MOP Technology Demonstration effort. These tests began in 2004 with DTRA partnering with the Air Force Research Laboratory. DTRA conducted flight tests from 2008 to 2010. In February 2010, the DTRA MOP Technology Demonstration transitioned to the Air Force as a Quick Reaction Capability Program. The tests are designed to test and demonstrate MOP capabilities to attack hard and deeply-buried facilities. The Air Force has had a long-standing requirement for this capability.
In 2009, Boeing was awarded the contracts to complete MOP/Aircraft integration. This entailed minor modifications to the MOP and to the aircraft. There were a total of 20 contracted.