The PnP game allows for stronger monsters simply by allocating levels to them - gone are the days where every goblin had the same HP range and did the same damage. An quick alternative is just to boost the stats, as Larian have done. Most encounters are matched to party capability by the GM, although there are occasions where an encounter might be deliberately out of the their league or particularly easy.
HP based on level is a D&D legacy that I don't like. It makes sense only if you insert a huge suspension of disbelief and agree that more heroic automatically means harder to kill because the hero is pumped full of life-giving narrativium. I would rather see major enemies made harder to kill through having better skills or resources than just becoming less vulnerable to having swords stuck through them.
