I don't have super strong feelings about whether news outlets should use the word 'lies' to describe Donald Trump's lies. As long are they're super clear about how he's saying that p even though p is false, that seems to me to be the important thing. The controversy over whether to use the 'L-word' doesn't really interest me all that much.
That said, I did find it pretty interesting to read NPR's description of why they don't call Trump's lies 'lies'. The basic thought is this: in order for something to be a lie, it has to be said with an intent to deceive. So in calling something a lie, one is in part making a claim about the intentions behind it. As NPR's Mary Louise Kelly puts it: "without the ability to peer into Donald Trump's head, I can't tell you what his intent was. I can tell you what he said and how that squares, or doesn't, with facts."
This is an epistemological claim—a skeptical one. It's often tempting to say that you can never really know what someone is thinking, because all you really have to go on is how they behave. But skeptical temptations are funny things, and there's probably good reason to resist a lot of them a lot of the time. For example, notice that it's also tempting to say that you can never really know anything about the future, since it hasn't happened yet, or that you can never really know historical facts, since you weren't personally there. At an extreme, Descartes famously argued that you can never really know anything about the external world, since you might be the victim of an evil demon who is manipulating your senses in a way that doesn't correspond to reality.