I play tank, I've played all the tanks... these are the things I have found to be dumb or make no sense.

Paladin:

Divine Veil: Why do I have to heal for it to proc? Why does it not affect me? Dumb.
Cover: Why does this cost Oath? Dumb
Riot Blade: Looks dumb (IMO) replace it with Rage of Halone

Warrior:

Shake It Off: Why does this remove buffs I already have on for a 2% boost? Dumb!
Orogeny: Why did this need to exist, just make Upheaval and AoE. Dumb
Inner Release: Not dumb but I do think a duration buff would be nice.

Dark Knight:

Abyssal Drain: Why is the cure potency so low, buff to 400 cure potency. Dumb
Oblation: What is this thing? What does it do? Whack a 200 cure potency regen on it.
Blackest Night: Why do I get punished for using this if it doesn't break. Kinda Dumb

Gunbreaker:

Heart of Corundum: You had a chance to give it 1000 potency ... why not take it?
Double Down: I don't see why this had to be 2 cartridges.
No Mercy: Maybe increase the duration a bit, I don't know just saying.

Shirk:

Can we just make it so this isn't needed, I know I know dumbing down... but do we really need to have this? Just buff taunt and get rid of this.

Those are the things I think are dumb, feel free to add what you think is dumb ... or call me dumb IDK.