I hear you.
My point was, though, that most science writers gravitate toward that beat because they already have an interest in that field--they've studied it, etc. They often do fellowships in science writing, etc. Just as a number of journalists who cover legal affairs are also lawyers.
But ultimately, they're journalists. Their job is to interview other people--the ones who are the experts--do reporting/research and then distill what is often complex, wonky material into a narrative that is easily digestible, relevant and informative for the lay person. (And any journalist worth his/her salt will go back to the experts and fact check with them.)
That's a skill, too. Personally, I wouldn't want to read a science article by a scientist who isn't also a trained writer/journalist.