Though, one shouldn't discredit Magefist if you're using another offensive ability that's fire damage (i.e. HOTA/Smash). It may reduce the damage on Furious Charge comparatively to Vile Ward, but it will increase the damage of the other. Don't forget that the fire chain from Maximus ALSO has its damage increased by the fire dmg% of Magefist as of 2.1. That's why I said that if we're focusing exclusively on Furious Charge, yes the Vile Ward is better in all ways, but I was thinking more generally. That fire dmg% from Magefist increases my HOTA/Smash damage and when fire chains + HOTA is going off on an enemy, it's an incredible amount of damage - comparatively so to a Furious Charge. I've clocked my Furious Charges critting for 22-26 mil (non WOTB), and about the same for a HOTA/Smash+Fire Chain combo. It's good damage output for when FC is on cooldown. I've seen videos of some Barbarians hitting waaay harder due to using more offensive passives or just straight up having better gear.
I guess it just comes down to play style. I do like maxing out efficiency, but not to the extremes the top players would do it. My cooldown reduction is only at ~19.7% (Raekkor shoulder enchantment, helm gem, a bit of paragon), so I don't have the cooldown reduction that keep Furious Charge mostly up (especially against a single target).
Edit: Dammit, now I can't think of anything but D3 at work. I've been thinking that I could greatly increase my damage by giving up some of the defensive passives I've been using and going back to using Rampage or Brawler or something. Been using Superstition for Fury generation and elemental defenses. I should track down a Furnace and give that a shot instead of Maximus (or at least switch it out for elites). Lots of stuff to try.