I can’t really see the SoJ being very good, at least for Barbs. Because nearly all of our builds rely on doing damage with a single skill.
(My own reading of the affix is that if you have, say, 19% fire, 17% cold, and 15% phys, and 0% lightning on your gear, then all of these would have a bonus equal to the highest, i.e. you would have a bonus to all 4 elements of 19%).
H90 does all its damage with Frenzy, and this is baked into the set.
Zodiac Rend does all its damage with Rend. Technically, it is possible to do a bit of damage with WW, but not much compared to Rend.
Pro-Slam does all its damage with Seismic Slam. MOTE gives a big bonus to a bunch of skills, but only SS and EQ have the supporting items to be relevant, and you can’t equip all of those items at once.
Vile Charge does all its damage with Charge.
IK HOTA, R6 HOTA, and LON HOTA do all their damage with, well, HOTA.
The closest would be Leapquake… it might be a small advantage to be able to run Fire EQ, phys SS, using BoD and FotVP, and getting 40% elemental on each. But, where are you going to put the SoJ? Losing F+R costs you a bunch of damage. Losing BoM probably means you die. And if you were going to swap out BoM, CoE would be a vastly better choice, as it adds considerably more damage.
So: it’s definitely not meant for us. Maybe it’s intended to work with the new DH set, which fires primary skills while you channel strafe. I’ll have to look at the numbers a bit and give it some more thought.
Edit: no, it doesn’t seem like that’s it, either. The new DH set doesn’t actually buff Strafe damage at all.