This form is very useful as the open string is the 5. The 5 is a great pickup note in a melodic line. Also from a technical standpoint, this form is less demanding on your fretting hand than the other three inversions.
I will demonstrate utilizing open drone strings to create textures when playing these 4 notes-per-string Add 9 arpeggios in 3rd inv. For example, if you are playing the arpeggio on the 3rd string, the chord is CAdd 9. You could use the 1st string open as a drone which would be functioning as the 3 of the chord. Be sure to explore this concept on your own.