Given that recovering from the worst outcomes in the game are generally six rolls of 3-4 dice away, fear requires more than just willingness to invoke that situation (e.g. the DM turning on the Random Meaninglessness Character Death spigot). Instead, fear requires consequences, the potential for the situation to turn out to the positive (or less negative), and a certain amount of control in the hands of the players to affect that potential. The more a character has to lose, might or might not lose, and the player has the capacity to influence whether they lose it or not, the more investment they have -- creating the opportunity for fear.
So fear = bad thing is false.
And also an argument not made in-thread.
Prior to 5e PCs died at zero (or neg10 with the death's door optional rule) and every single point of damage needed to be healed at a
situational day by day rate and spell slot by spell slot and without unlimited cantrips while lacking full BaB progression the cleric wasn't going to be keen on dumping all of their slots healing
everyone back to full. Sure they might burn a couple bringing the tank back to the upper 80% or so, but they aren't going to and generally couldn't top off everyone. That led to the situation where a 2-3 point hit to the wrong PC could be scary because the player knew their cleric couldn't waste the heals on them when they might need it for the tank later.
I would hesitate to lay this all on 5e. Various forms of this have shown up for quite some time. 4e's healing surges were a lower total than 5e's long rest plus short rest (/hit dice expended) recovery, but it was still a fixed % of total HP/day recovery. In 3e, once people discovered how cost-effective 1st-level wands of Cure Light Wounds were, having between-encounter healing being a significant cleric spell slot expenditure was a playstyle choice. Even before that, exactly how hard it is to find a spot to rest back full (and whether the time spent doing so was really a costly sacrifice) was significantly group-dependent -- with groups that just rested back to full whenever until the DM got a wild hair about tracking rations being at least common enough for
Knights of the Dinner Table to lampoon it.
Fear in PCs requires that the system present plausible risk like that to the players coupled with a hunger for more. Will our resources hold out? If we work together better and really stretch can we get MOAR of the phat lewtz we know that we really need and bigger experience payoffs? Can our carrying capacity carry all of the supplies and equipment we expect to need?... Obviously not... Which do we need now and which can we plan to go without? How can we stretch each HP of life?...
Very much so, and I think a oft-ignored flipside. The characters need something to risk-not-getting to make the stakes meaningful. As mentioned above, just dying is of limited value with another character a few rolls away*. Situational/plot success is actually pretty motivating, but situational. One thing I think the game has minimized as of late (to the detriment of a fear element) is those payoffs. That Phat Lewtz (or Lootz, by my preference). Money is relatively meaningless after a certain point. It was in AD&D 2e as well (optional rules notwithstanding), unless you thought you were actually likely to hit name level and cared about the castle&command portion of the game. However, back then magic items (almost exclusively random, as loot) and found spells were a huge deal -- perhaps character defining. All the modern editions have added non-loot ways of defining characters*
, but 5e has also made the most inroads towards making magic items optional**. In terms of setting up the situation where you(r character)
might want to stay in the dungeon a little longer, but you don't know if you should risk death for the marginal gain, there really aren't a lot of built in incentives.
*slow xp progression and/or rules about where you start if you have to start over might help here.
**honestly 2e did as well, with all the proto-feat stuff found in the later uses of proficiency slots, and the Player's Options books, etc.
***and the attunement system's 'I found an item, but it isn't worth giving up what I'm already attuned to' at least rivals AD&D's 'find a magic weapon to which you are not proficient' in terms of potential for finding a magic item not really being a reward