It is the player's own fault for dieing right before the boss, it usually means that they weren't prepare or were getting overconfident. I just don't see why they should reward you for failing to survive. Death should come with some penalties, and not receiving loot or exp(along with losing some durability.) seems like a good penalty.
Keep in mind that some characters will be more effective "tanks," (honestly hate using that terminology in reference to diablo gaming, but it suits this situation), distractions, or simply first-to-jump-in. Consequently they'll be in more danger. I don't think it would be wise to conclude every death is simply over-confidence or stupidity in a party situation. Many times it may simply be that the room was a death-trap and the stars aligned in a very unfortunate way.
Of course I never had a problem simply running back in D2 (when I was playing softcore and had that option), but this system alleviates a bit of the frustration. I don't see anything inherently wrong or potentially abusive off-hand.
I think it would be better if they went with the "you helped fighting the boss, you get the loot/experience even if you're dead" path. Something like you die, then your "ghost" can stay there and see if your friends/teammates can finish the boss and you get the experience and drops normally, you just going to have to "respawn at town" and teleport to one of your friends (assuming you can only do that when they're out of the battle).
I'm worried exactly with dying right before someone lands the finishing blow. Basically, you played an hour to finish a dungeon, helped in everything, wasted so much time to get to the boss, helped a TON in defeating it, but because you died, you don't get anything.
Yeah, I know D1 and D2 were like this, but D1/2 also had stuff drop for everyone, do we want such mechanic back? Isn't the idea to improve on what's "broken"? If you're revived afterwards you won't get the xp nor the loot, how great is that? Everyone playing defensively instead of helping because they are afraid of dying and not getting anything - yeah, that would work.
They used the reason that people who are getting "rushed" would have to be careful not to die, but if they don't want "rushing" in game, just remove it altogether (by not allowing low lvl chars to teleport to high lvl chars/dungeons), instead of putting in a mechanic that can potentially frustrate other players.
In retrospect though someone could land 1 or 2 hits on a boss and die basically free loot for them than?
Thats why I said make drops level dependent or something to prevent loot farming. If their high enough level to be there and get loot I think it's safe to assume the person helped in making it happen. If nothing else should we punish all the legit players who do help making the kill just to punish the occasional lazy bum who hangs back and leeches drops?
Realistically the current system where if you die you get squat actually promotes people hanging back and minimizing risks instead of going for it. If I have any chance of getting killed and missing my drop I'm going to do everything possible to stay alive and take as little risk as I have to.
It also means I'm not going to play a 'tank' toon. Why risk it if I'm going to get screwed outta drops?