Some of them are just providing back-story and immersion. Some of them are fan/player submitted.
However some let you know about upcoming Community Goals that you can take part in, or let people know about discounts available as a result of past CGs. Some of the Galnet articles are amusing - such as the "bug" which caused the FNS Nevermore to get into a firefight with the Hudson Dock, or the Code group attacking another Farragut vessel and forcing it to retreat. No doubt when Powerplay comes in the next release, Galnet articles will be even more important to keep an eye on.
And then, you have all the fuss about the Unknown Artifacts and the conspiracy theories related to them.