Turn off vibration notification for ALL apps at once
Update: Android Pie (9.0) finally allows you to disable all the vibrations. Go to Settings app &gt; Accessibility &gt; Vibration. Some ROMs still don't have this option, in which case you may want to check out my old solution.

Old solution - applies to Android Oreo or older (&lt;9.0):
Stock Android does not have an option to disable all vibrations. This frustrated me as well, so I made an app that can turn them off system-wide - https://blade.sk/projects/global-vibration-toggle/
A rooted phone is required, as there is no API for disabling vibrations.
The app is basically a user-friendly wrapper for this shell command: chmod 444 /sys/devices/virtual/timed_output/vibrator/enable.