I wish more fantasy RPGs used their own player conveniences as more than just player conveniences. Like, FF7's big "what the hell" moment when you can't just use a Phoenix Down on Aerith.
Dragon's Dogma has spoiled me on this. You can revive any fallen named NPC if you have a wake stone. They even get put in a special room for you to visit if you forget their body long enough, so you can never lose a vital NPC while still having chaotic, emergent action with monsters rampaging through town.
Phantasy Star 2 has a named NPC die and it has a weird excuse why you can't revive her at the clone labs, even though you could just fine up to that point.
Also when everyone else was like "omg no character has died in an RPG before" youth me was sitting there like "is phantasy star a joke to you?"
BG3 only lets you use revivify on characters in your party. D&D says it only works on those who wish to return (player characters always have unfinished business) but some dead NPCs definitely had something to live for, but are screwed
Don't know about 5E but 3.5 at least allowed a fresh corpse to be brought to a cleric and revived for a fee, if your own party had no means of True Resurrection. The DM could always be a dick and claim they don't want to come back, I guess. But if they are truly important to the campaign, surely that would be counter productive.
3.5 also allowed my druid to become a Master of Many Forms which is quite OP
That game petered out, I wouldn't mind a one shot set in its future: that character and it's other overpowered party members aged and seeking a death in battle to trigger their contingent spells to reincarnate
My headcanon is that when a character "dies" in battle, it actually means they are in critical condition, requiring more powerful healing magic or items to get them back on their feet.
Of course, there are some exceptions. In Phantasy Star 2 and Cyber Knight the characters die for real and are replaced with clones.
2 or 4? 4 Japanese was 2 in the US. 6 Japanese was 3 in the US. We actually got robbed of a couple of gems there. 2&5 were pretty good if the translation I found was accurate.