Have you ever wanted to use 2 apps simultaneously on your phone? For example watch a YouTube video while browsing the Internet on chrome or use your music app while using Facebook. Now you can get multi tasking on your android device (rooted).
Have you ever tried to download a movie from torrents? It takes time to download, sometimes a lot of time. Time that could otherwise be spent watching that particular video. Or maybe you just suddenly changed your mind, and want to watch something else. Do you wait for the torrent to finish downloading again?