Because controlling language controls the agenda.
Ann Althouse - who tends liberal - makes a good point, several, actually:
Come on. Add the obvious: The media perceive the Gosnell story as a threat to abortion rights.
By the way, why are we calling what he did "abortion"? Just as a matter of clarity in the language. The grand jury report says that his method of ridding women of their unwanted late-term pregnancies was to induce labor and deliver the child. That's not abortion. That's childbirth. We're not even in the gray area where a strange term like "partial-birth abortion" could be used. It was complete birth, followed by murder. Why don't abortion rights proponents come down hard on that distinction? He wasn't an abortionist (in most of these instances), but an obstetrician-murderer. If abortion rights proponents don't want to talk about that, I'd like to hear exactly why they have a problem.
The answer to the second question is the answer to the first question.