Following the bugs plaguing iOS 8.0.1, Apple has stuck to their word and brought back the HealthKit apps to the App Store following the release of iOS 8.0.2. These were taken down initially because of the aforementioned bugs and they promised to bring the apps back by the end of September. So, all iOS 8 users can now go back and download the HealthKit app of their choice.
Source: Ubergizmo