Why is this more philosophically important than a neutral attitude? Why should the media presume innocence before guilt?
Actions and attitude are two different things. You can be neutral in terms of your attitude but when it comes to how you proceed in terms of your actions there is no third option, you either align your actions with trust or you align your actions with distrust.
In our criminal justice system, a hung jury (symbolic of neutrality) would result in an acuital, which means treating the defendant as if he were innocent and letting him go (aligning with trust). The only other alternative is to keep him incarcerated (aligning with distrust).
Because neutrality does not translate in terms of how we act, a default position is logically necessary. In the criminal justice system you can either be innocent until proven guilty or guilty until proven innocent. Your default mirrors your values. As a society we value protection of the innocence over punishment of the guilty, so we choose innocent until proven guilty.
So what should or default position be with regards to our institutions? Should we trust them until given a valid reason not to, or should we distrust them until given a valid reason to trust them?
I don't think this is a difficult choice because the latter is untenable. The US has become the most accomplished and most powerful nation on earth as well as the envy of the world (although that's questionable over the past decade). We accomplished this because of the strength of our institutions, and that strength is a direct result of the trust we as nation have had in them. Institutions that are not trusted are useless.
Also because it is nearly impossible to prove trustworthiness, that's almost like proving a negative. I could do the right thing 100 times, doesn't prove that I'm not waiting for the right opportunity to abuse my position. Meanwhile if I do the wrong thing once it proves I'm not trustworthy. There's an unavoidable imbalance there weighing against trust, the only way to balance out is through trust as our default.