"The Wikileaks Party is a minor party with a progressive agenda. Parties like that need all the support they can get, particularly in the early stages of their development."
'Objectivity', as defined and practiced by mainstream media, can actually be code for 'the right bias'.
The attack in Boston involved people 'like us' - including some Australians - being attacked very unexpectedly, so it is not surprising that Western media have a greater incentive to report it. But that word 'incentive' gives a clue as to why these news values are problematic.