10 minute barbarian rage is completely incoherent

[Snails]

IMO any player option who's core identity is directly tied to a set duration is going to be a mess. DND hasn't handled time well since 2e.

You could probably map 90% of the issues with 5e back to this.

I did not think about it that way, but I have been edging to your conclusion. I want to revamp the Barbarian and emphasize Reckless Attack as their core ability, and have improvements at higher levels.
Rage becomes something more varying and tied to subclass. In a similar vein, I was also thinking that the Ranger's core ability is Hunter's Mark and should not even require a spell slot.