Metal is one of those genres that tends to limit the potential of our chord work. The massive amounts of distortion make many chords, especially those containing open strings, unusable. This leads many players to rely on power chords instead, de-emphasizing the major or minor melodic qualities that can only occur in a chord that contains a third.
There are chord voicings we can use that contain a third, certainly, but so much of the time, they lack either comfort or heaviness. The second inversion is sort of the best of both worlds, retaining the heavy fourth of the power chord while adding a third.
For examples of all the things we can do with this, take a look at the following video:
Thanks for reading/watching!
By Kevin Goetz