Why?!?
Anet doesn’t treat endurance as skill that can just be ‘reset’.
When you die your endurance bar is still slowly rising (unsure if it is still affected by traits when your dead). The DD just has so much potential endurance that if you die with very little, it won’t be refilled on spawn.
Signet of Agility also “refills” your endurance, but it still only gives 100 endurance rather than 100%. Sigh…