Because honestly, this just keeps the door open for more crimes. Rarely is anyone ever good enough or honest enough - and neither of those conditions are required for addressing our heinous crimes against humanity, frankly. You just have to be good enough to know that war crimes and crimes against humanity are heinous, and honest enough to produce workable evidence that can be used to produce justice.
Assange is good enough and honest enough for that case, really - and if a person doesn't agree, they're a bootlicker thug. The WAR CRIMES have to stop. The CRIMES AGAINST HUMANITY have to stop. It doesn't matter one iota what sort of person reports the evidence - the evidence is real. The crimes are real.
Assange's honesty doesn't change the enormous magnitude of the victims digging their loved ones out of the rubble, one bit.