Some of the positives.
Stag form also has its own version of carnage which will also proc barb carnage. It's kind of like a mini heart of fury, havnt had much a chance to test it on lots of mobs to see if it chains kind of like heart of fury did in poe1.
If you go with the shifter druid, which you probably should, shifting out of a form you gain a large portion of health and the shifts also have natural armor making up for any lack of defense barbarians naturally have.
Not limited to big aoe damage like you were with a barb in POE1. Having access to the different shifts allows you to shift depending on the fight. If its a large group of mobs stag with its mini heart of fury is the way to go. If you are single target the cat attack speed modifier + frenzy + two one handed specialization as well as other party buffs can cause your downtime between attacks to be almost non existent.
You don't really cast anything with this build even though you have options for spells. If you wanted to waste some time at the start of the fight you could probably benefit from some of the buffs the spells have but once you shape shift you can't cast anything.
Wildstrikes don't seem to affect carnage. I'm not sure if the initial damage from the wildstrike on the target you hit is increasing the damage of carnage, I assume it does but the extra carnage hits don't an additional bit of damage from the wildstrikes.
I'm pretty low level so I havn't really gotten to do much yet, feel like if the wildstrikes did its own damage on carnage it would be pretty good. My only question is if the 15% extra damage done applies to the wildstrikes (Like heart of the storm + wildstrike shock)