I think this would be a highly coveted addition to the game for one big reason; not knowing how close a boss is to death forces players who wipe to make a judgment call: revive or quit. It's not fun reviving in the middle of a boss battle only to wipe again without getting anywhere, not knowing whether the boss is almost dead or even phased, and it's just as frustrating to give up on what could have been a victory with just one more revive. A visible life bar for bosses would almost completely eliminate this, allowing players who do end up wiping to make educated decisions based on a bosses current health, and deciding for themselves whether it's worth trying again, or if they're even capable of finishing said boss off without another wipe.
I'm pretty sure Three Rings wants it to be easy for players to figure out exactly how defenses/resistances/enemy HP works and how much each enemy has, so this would be a nice step in the right direction.
i totally agree with u it will help all of us.
sometimes u dont know if the boss is close to death and u dont know rev or not so thats a good idea.