A search for 'music download' now returns a message inviting users to try iTunes Radio. Swiping to the right reveals other music-streaming apps like Spotify. Previously, searching for music download apps would result in apps that could download 'free' Audio files from third-party file hosting sites. Apple has reportedly asked developers to "remove audio downloading functionalities from their app."
In areas where iTunes Radio is not available, you can still see those apps that illegally download from YouTube and other sites.
Another report from TechCrunch claims that Apple is also doing the same with apps that encourage users to watch/download certain apps in exchange for rewards. While this has always been against Apple's App Store guidelines, it seems they are finally enforcing it.
It is possible Apple is removing some of these apps in an effort towards cleaning up the App Store
ahead of iOS 8's launch which feature an improved store featuring a better search, an Explore feature, App bundles, and more.