They want to derive the maximum amount of exposure, page views and revenues from the leaked data in the form of web articles with ads, printed news papers with ads etc. Releasing the the actual data would be counterproductive to their own financial gains.
Somewhat ironic, I think.
(Yes, some of the 100+ news organizations are ad free, such as the mandatory tv license-paid state broadcaster/propaganda organ SVT from my country, Sweden, but they also have their own motives of wanting to control the data.)