I drifted away from D&D (and TTRPGs in general) during 3rd and 4th editions, so I'm ignorant of a lot of the history that gets us to 5e.
Why did morale checks as a mechanic not make it into 5e? It bothers me that, by default, bad guys fight to the death. Was it determined that it's easier/better to just let the DM decide if they surrender or flee?
History? Opinions?
IIRC/IMX, morale checks were a little-used feature even in 1e. (Possibly they were left over from Chainmail & the game's wargaming roots?) They mostly applied to Hirelings/Henchmen, and of course, to the unfortunate monsters that got in your way. Morale checks never applied to PCs. The groups I was in made little or no use of Henchmen & Hirelings - a generational thing, I think, older old-school wargamers seemed big on that kinda thing, and the books certainly acted like it was a thing to do. (Just not a thing we wanted to do - it was enough trouble for the DM to keep track of the monsters, and for the players to handle/RP their own PCs, without bunches of NPCs on the same side, as well.)
I thought morale had more or less vanished in 2nd, but that was the ed I gave up on by '95, and my experience with it was mainly continuing my old campaign in it, with so many variants I doubt my experience applies to the game itself, as written.
But, in 3.0, I'm more confident in saying, the game shifted very clearly to making PC, NPC, and Monsters more mechanically similar. NPCs had their own classes, and monsters got some feats PC didn't, and so forth, but monsters could have class level, and everybody could put ranks in skills, take feats, cast spells, etc... Given that apparent design philosophy, if there had been a Moral system, it likely would have had to have applied to PCs, and I doubt that would've gone over well. So morale just joined the many other nebulous 'keep on fighting' factors that were munged together as 'hit points.'
4e was no more inclined to make PC check morale than 3e, even though it returned rather dramatically to PCs, NPCs, and Monsters using very different rules. It did bring back morale checks in a sense, in that you could make an Intimidate check to force a bloodied foe to surrender.
5e is so wide-open to optional rules & variants, though, there should be no impediment to adding back morale checks...
...see:
The rules for Morale are in the DMG, page 273.
