Any content outside of the campaign is ‘one try’, hence a revive mechanic would be inherently against that.
I hope you mean uniques and not legendaries… there is never a way to loose legendaries for death.
Also that’s the point, if something nice drops you’re not supposed to let your guard down but instead clear the area before picking it up.
With a controller it’s a bit easier actually since you don’t need to click on the items, it just picks up anything still showed from your filter around the area, 1 per button press.
That is because zones aren’t instanced currently. That’s a performance decision that the devs would like to eventually change, but probably not anytime soon.