To see why that's so, just review some of what Manning said about why he chose to leak, as reflected in the edited chat logs published by Wired:
Lamo: what's your endgame plan, then?. . .
Manning: well, it was forwarded to [WikiLeaks] - and god knows what happens now - hopefully worldwide discussion, debates, and reforms - if not, than [sic] we're doomed - as a species - i will officially give up on the society we have if nothing happens - the reaction to the video gave me immense hope; CNN's iReport was overwhelmed; Twitter exploded - people who saw, knew there was something wrong . . . - i want people to see the truth… regardless of who they are… because without information, you cannot make informed decisions as a public.