-Large enemies frequently slash around large weapons in tight spaces killing you, but if you try to swing your sword it clanks against the walls.
Okay, granted. The way weapon collisions work with terrain is poor and somewhat unintuitive. Basically, each weapon has certain "startup" frames where a collision will happen, and then "active" frames where the weapon will pass through colliding terrain because it's basically too far into the animation to do a rebound without problems.
This is sensible, except in DS3 it admittedly creates some really bizarre situations where huge weapons can swing freely in tight confines (because their startup frames won't collide, just the active ones) but even very small weapons like twinblades bounce off seemingly every bit of terrain possible.
-Enemies can swing their weapons through walls and doors (such as prison gates) to hurt you
As you might surmise from the above, you can do this as well if you have a larger weapon with the right types of swing. The only real advantage the enemies have is that non-"human" enemies usually don't have any collision with environment checks for startup frames.
-Enemies can take an incredible amount of fall damage, but you can barely survive a fall of much lesser height.
Depends on the enemy type. Human enemies (invaders, NPCs) actually are treated the same, and you can cheese some of them (Lautrec or Anri, for instance) pretty easily by baiting them into a fall or pushing them off a ledge.
They seem to handle other monsters on a somewhat unpredictable case-by-case basis, though as far as I know a "guaranteed lethal" fall kills all forms of monsters, it's just that non-lethal falls sometimes will do reduced/no damage to them. This may simply be due to extensions of factors that affect player fall damage. (You take less fall damage if you're not wearing armor in DS1, and in DS3 you take less fall damage if you have higher Dexterity. The way the game is programmed many enemies may logically be treated as having no armor and very high DEX.)
-Thick swampy water slows your movement, but enemy movement is never affected (even enemies that aren't native to swamps).
"Human" type enemies are equally affected by mires. I'm guessing you mean things like the drowned corpses, giant crabs, basilisks, etc.
Personally, I don't like "mires" as part of the level design at all--I think it's a really dumb thing to spend so much time fine-tuning the responsiveness of controls and animations and then build entire areas where the game controls like damp ass--but some players seem to love them, so what can you do?
-Environmental hazards (poison, lava, etc) illogically don't affect enemies.
They actually do. The statues in Cathedral of the Deep can poison the Cathedral Knights if they stand in them. Human invaders (with the apparent exception of Yellowfinger Heysel) can also become poisoned, toxic, or die from walking into lava. For instance, if you want to kill Knight Slayer Torrig you can lead him up to the nearby bridge over the lava room and just bait him into falling in.
It's true that enemies that actually spawn in poison or lava (leeches, lava slimes, etc.) aren't affected by it, but that... makes a certain degree of sense? Try baiting other enemies that
don't spawn in the hazard into it; it will usually work, though keep in mind many enemies have very high Poison/Toxic resistance.
-Using a great soul from a boss only to find it was only worth 10,000 when you have souls you have picked up from corpses that are worth the same or more.
Yeah, fair dues, this is just a total crapshoot in DS3.
I don't know why some Transfusions have a soul cost attached to them, when the soul cost should be assumed because you're using the soul to make the weapon instead of expending it to get the number of souls it would be worth. (ie, the weapon already by default costs a number of souls equal to the value of the boss soul used to make it)
I don't know why the value of boss souls is completely unpredictable--Deacons of the Deep and the Soul of a Demon are worth 20k, the same as the last boss and more than almost all other bosses in the game!--or why the value of boss souls hits a wall at 20k and stops.
I don't know why the value of boss souls does not scale with NG+, even though
normal soul items (as found on corpses) are in fact scaled to NG+.
I don't think From knows either. I don't think anyone actually thought very much about any of this.
-Your blood stains are frequently in the wrong place when you return to retrieve your lost souls
Your blood stain is about 3 seconds "behind" where you were when you died. This is to make it a little easier for you to recover them, especially if you died due to falling damage. That's generally a pretty good system and better than the alternative.
-Kicking is the same button press as your standard sword swing. You press RB to swing and you have to press RB + up to kick. This can lead to obvious problems and is just awkward.
Yeah, kicking as an input is not particularly reliable.
-Enemies that not only snipe you, but fire projectiles that home in on you like a charged plasma pistol shot from Halo.
Homing projectiles are kind of lame, but basically needed because the speed of projectiles in the game is generally quite slow. If they didn't home in on you, they wouldn't really be a threat at all.
The alternative--making them non-homing but faster, as with spells like Soul Stream--would make it really hard for players to manage situations where they're being peppered with ranged attacks while trying to fight/avoid enemies in a melee.
-Enemies often have incredibly weird hit boxes and can hit you when they clearly missed by a wide margin.
Most of the hitboxes are really good. There are just a few attacks--mostly "grab" attacks--that have always been dubious, and a few specific enemies with really crummy hitboxes (Sulyvahn's Beasts are just awful).
-Certain classes and attributes are extremely worthless in comparison to others, frustrating players that don't have experience with the "way these games usually work."
I'm assuming you mean builds, because starting class is basically meaningless.
To be honest, there's no truly worthless build at the moment. The speedrun strategy of choice is actually to run a
LUCK build of all things, with a quality weapon. There are strong STR and DEX builds. You can find videos of people beating the game literally only ever using Pyromancy, Miracles, or Sorcery.
You might have trouble finding the right weapon or spell to make a particular build "work", but making an actually worthless build is surprisingly hard compared to previous games.
Also, I can't believe you complained about all of this stuff without saying one word about the true bullshit: enemies don't have stamina. They have guard-break to "fake" it, but it's also the responsibility of the AI programmer to insert "breaks" into their routines to simulate stamina recovery after attacking...
... which worked fine in previous games, but someone involved in DS3 dropped the
fuck out of that ball. There are some seriously disgusting unshackled boss AIs in this game that can spam attacks without openings for absurdly long periods if you have a run of bad luck in terms of their attack RNG.