Android has silent mode, and there are apps that can silence all six volumes with a click. But while this silences sounds, there are lots of apps that have vibrating alerts that will vibrate even in silent mode. This can be good if I am using my alarm app (I leave my phone on a table and the vibrate noise wakes me up). But I don't want any other apps vibrating. Yes, there is nearly always an option in individual apps to disable vibrate, but I might want to have these apps vibrate when I'm not asleep, and I just think it would be cool to have peace of mind with a disable vibrate widget (except for your chosen apps).