Zardnaar
Legend
3.5 hitpoints were problematic. Or rather spells did not deal enough damage to warrant using them. A 5d6 fireball at level 5 was lousy. Better cast a save or suck spell until it sticks.
3.0 actually was a bit better in that regard but not a lot.
3.x suffered from a big misunderstanding. Especially 3.5 that embrace bugs as features:
3.0 was most probably built under the premise, that AC does not scale that much over 20 levels. So fighters would start getting close to automatic hits after a few levels with their first attacks and still a good chance with their second. Someone with 3/4 bab like the monk would also hit well enough soon.
Because this was not explained well and coming from AD&D, where not being hit was often mandatory (prpbably we played that wrong too), DMs, me included, tried to increase enemy AC too much. In this process, fighters started to feel useless, their second attack not having a chance to hit. And thus HP felt a bit too high to get through. So fallback to save or suck and caster dominance.
Kind of a start. I will point out a 3.5 fireball is comparatively better tha a 5E one except maybe lvl 5.
In 3E, an efficient (not optimized - just efficient) 3E game, we'd often see monsters that the DM spent quite a bit of time assembling go down before they did anything. They might as well have been a potato. I recall one battle with a Frost Giant Jarl and its mount, a Frost Drake (a dragon without the smarts) that took me an hour to craft - but that the PCs killed before either could act.
This is bad design.
If anything is commonly rendered irrelevant in actual play, it is problematic. Other than fodder, a monster should survive to the end of the first round in D&D for it to have some relevancy. There may be the occasional exception to the rule (high damage crit), but it is bad design to have monsters that are easy to fell in
Let's say that a 2nd level party of 5 PCs encounters 2 ogres. This is a 'hard' encounter by the books. Those slow moving ogres will other go after 4 or 5 PCs have activated. If the PCs focus fire, you can often get 10 to 15 damage per PC on these monsters. If the ogres have less than 30 hps, there is a real high chance that one, or both, of these theoretically significant threats, will fall down before they do anything in combat.
In 3E, they had 26 hps. In 5E they have 59.
Which is a better game experience?
The party rolls for initiative. The barbarian rages and deals 2d6+5 damage. The rogue then goes and delivers 2d6+3 with the main hand sneak attack and 1d6 with the off hand. The ranger deals 1d8+1d6 (Hunter's mark) +3 with their bow. Then the warlock blasts away for 1d10+1d6+3 with their Eldritch blast. At this point the monsters have taken 1d10+1d8+6d6+14 damage - or about 45 damage. That is one ogre down and the second nearly down as well. If the fifth PC gets to go, the 52 hps of both ogres may be gone before they do anything! In 5E, you'll probably still have both up and doing something in that combat. In the 3E model, the ogres could be ogres, deinonychus, or black bears - it wouldn't matter. The difference between them would be trivial. In 5E, it matters as they're going to get to act.
5E was designed with intent and knowledge based upon the prior editions. As with most of the decisions they made for it, they improved the situation with their design.
And if you lowered the damage using 3.5 hit points or upped the ogres defenses?