Because the Federation was not xenophobic. Everyone knew who they were, and where their planets were. Let's say they adopted the technology for use on Earth. Everyone knows how far the Earth is from the sun, and how long it takes the Earth to travel around the sun. If someone knows the date, then they know Earth's position, regardless of whether they can "see" the planet or not. Also because it sterillized the population of Aldea.
Because most of the Federation's enemies have gravitic sensors. Invisibility does nothing when your planet has a huge gravity signature.