Terrorists are looking for reaction. We can fairly assume that they are going to tune their actions toward public exposure in any case. If reporters did not choose to report on any terrorist actions, they would simply find the next best thing. Perhaps spending more time working terror at the local level or moving toward bigger and more harmful actions in an attempt to gain a response.
While on the one hand you may be exciting evil doers who's actions were taken to prompt this kind of notoriety, you may also be leaving the public blind to potentially dangerous situations they may not otherwise have gotten themselves into. Some may say that IS stopped kidnapping reporters because there has been less publicity about it, but it might also be said that fewer reporters are putting themselves in those situations.