It's not that there's anything wrong with aspiring to be unbiased; the problem arises when someone really thinks they are unbiased, or claims to be unbiased. You get this a lot in the MSM; the Guardian constantly exhorts it's readers to subscribe, to support unbiased journalism.

I prefer reporting that wears its biases on its sleeve. Regrettably The Guardian squeezed out most of its most interesting writers, apparently by repeatedly spiking their stories.

Yeah, Truth and Justice are platonic abstracts; nobody thinks they exist in the real world. But people do believe that unbiased reporting is possible. It isn't.