Cap'n Kobold
Hero
Unless your DM just flat-out throws an effect that one-shots you (which as you note is rarer in 5e than in early editions), losing HP in much more incremental and has options that give you at least the illusion of a fighting chance over the rounds in which you take it until you go down. You are able to interact and participate in the game, and there may be things you can do to reduce that damage. I personally would include magic that just deals HP damage in the same "less frustrating" category as weapon users.Well, all monsters were scary in 1E and 2E because PCs all had lower ACs and HP. So getting your ass kicked was easier in those editions by even just hit point damage.
Starting in 3E they did start to make PCs heartier-- more character options to built up defenses and such-- so the fact that they used magic as a way to not make those players too cocky was their answer to the situation. Seemed like a valid reason to me.
Personally, I really don't get so many people's aversion to magic in D&D? Why getting your ass kicked by weapon-users and those that just target HP is somehow more acceptable than getting your ass kicked by powerful magic? I'm sure you all have your reasons... but I personally don't get it. To me, losing a fight is losing a fight, whether it's by magic or by steel. It sucks either way.
Compare that with getting stomped by non-HP magic: you're out. You might get just a single roll, and bad odds of making it. It is entirely possible at higher levels that there was no chance of resisting it.
You're out of the fight. Maybe you get to roll a die to try to break out on your turns, maybe your party can break you out. Maybe the DC is too high and/or they cannot. Either way you don't get to still interact or try different strategies: You're just on hold until you're allowed back into the D&D game.
The outcome might have been just as inevitable. But the fight that you lost through HP damage will probably have been much more fun, and much less frustrating than the one you lost by just rolling average on a single D20 roll.
Not all effects that require saving throws deal HP damage.The more difficult save is mitigated by the increase in HP for the PCs, which provides a different layer of protection against the breath weapon and favors fighters, barbarians and the like.