> I don't understand why this would excuse anything
I don't see it as an excuse, just as an observation of reality. Journalists can be misled by their sources. They may misinterpret data or make mistakes. They can have ulterior motives, or they may see the world through different glasses than you/me (e.g. conservative/liberal oriented news outlets). They may be pressured by deadlines to put out subpar quality material. There's noise amplification and echo chambers due to the role of social media. There are many reasons average journalism today might not be up to some standards.
The way I tend to think of it is: trust but verify. Some things matter directly to my personal life and it's in my personal interest to verify that I have the correct information about them. Why then, should I trust the (possibly exaggerated) interpretation from some WSJ journalist on some recent research paper rather than doing my own homework?
News about Theranos at this point, for example, is not one of those things that directly affect me or my family, and the accuracy and outrage of this story is of only mild entertainment value to me. Recognizing that, I can choose to consume news about it with the implicit understanding that I'm probably getting sensationalized editorials with no more value to me than a random hollywood movie, and not some data source that I should be investigating.