Johannes said:
HP bloat is a design choice of itself, and I don't see any reason why less random damagedealing calculations would inevitably lead to it.
It's not a choice, it's a direct result of the glancing system. When damage is delivered per second, no matter how small, then you must have enough HP to be able to absorb it long enough to have a chance to win.
You have 4 party members who, let's say, do 40 dps each avg. The glancing blows reduce damage: on casual it's 3/4, normal 1/2, hard 1/4, nightmare 1/10. So, on casual glancing blows of my party members do 4x30 dps =120 dps. In 10 sec that's 1,200 hp. In a full minute it's 12,000 HP if they only do glancing blows, but they do a lot more, they do special attacks which always hit and are hundreds of points. So, an enemy that's expected to last a minute against all party members should have 20,000 HPs.
But that's on casual, right? Well, do the enemies on Hard have less HP? No. They often have more. Even if they don't and the HP remain the same, you do a lot less damage, the enemies resistance is higher, but it takes you a lot longer to go through the HP bar.