a) if we take G1 as is, it does not really hurt game as much as you think. in fact, dialogue of G1 is the weakest part of the game, because it works a lot more like adventure game where you click through options, or characters just monologue at each other. By default, PBs desire to make everything more realistic of whatsnot, lead them to a voiced protagonist. Without voiced protagonist, we would not of course get all the memes, but neither do we get any options, and also get stuff like Lester's dialogue in meeting quest in english being literally pieced together from some crazy shit. Some say it's Sleeper affecting him.
Reading a dialogue line and then hearing your character say it again is already a suboptimal way of doing things, especially for a game like Gothic, where you're supposed to think what you say.
b) gothics lethality ends on your first ok armor + jewelry of protection. enemy ar seems to be inneficient to defeat hero. G2NOTR drags this much longer, but regardless, a system where if your armor is high enough you IGNORE ALL DAMAGE (in G2 it's minimum 5 damage) is not great anyway. you, of course, should be torn by wolves without good armor. semidecline but it's a question of damage taken slider or whatever.
c) in an era of consoles, most likely we would not see any freeform spatial maneuvre or ability to direct attacks with the mouse. Gothics combat with locking target is still, compared to contemporary action games, pretty shit, and it is very easy to cancel animations of enemies; but guessing patters, having enemies running past you and freedom to block and attack when you want it is better than button prompts. Let's call it, a 0.5 decline.
d) G1 armor design has some fantasitis, like demon face on gate guard armor or retarded pauldrons, but armor is generally consistent and fantasitis is subdued. All armor seems to be something that inmates roughly patched together from things more common for their camps and all follow an obvious upgrade path. Of course, modern developers are more obsessed with how cool it looks and are obvlivious to such minute detail. A decline.
e) you might think it's a small issue but it really shows the more modern approach for an audience which can't pay enough attention before going back to twater or whatever, and needs all the explosions and dramaturgy. One cannot just sit on a bench and wait until random mudcrab finishes frying their meat and talk calmly, you need all that extra fanfares and serinades and cutscenes.
Gothics already have cutscenes, they come naturally from living world around you. You speak with someone and you can see smith mashing an anvil or other characters talking near, or sun setting and torches getting lit. That's all the decorations you need.
To me it seems both missing the point of how gothics behave and the rough mood and appeal of the originals.
also there is no narrative reason to explode anything in the beginning, game has rising tension through the story as good stories should be.
f) a pointless change but doesn't really hurt the game unless you also begin beating the fuck out of shadowbeasts with a stick.
g) there is chosen one prophecy in both games. in 1 it's Xardas who tells you about it, in 2 whole plot suddenly takes a metaphysical take on it, where hero is supposed to be chosen of innos (goodguy) and dragon of Beliar. In G1 all three gods are more of a part of three faced diety, as you swear a magic oath that in the end, you will go to land of Beliar. Diego, of course, shouldn't treat hero as chosen one, but to an extent he is. I would remove this whole dialogue from original game and reshuffle narrative so it would look much more that main hero achieves victory through being clever and having friends instead.
h) tbh some resource management in combat wouldn't be unwelcome, since gothics usually end with 250 potions of all kinds and 7000 meat and you can just rest on a bed. Just not the hide behind cover or press f for magic inhaling system (although you can hide behind cover and gulp potions in pb games).
i) as long as you can turn post processing, blur, and other shit effects it's not a big deal. It does, however, reminds you that PB are actually masters of some very small but interesting effects, like forest looking like wall of trees in G1 (some sort of fog/texture). They are also known masters of evenings and nights and mood, and did it with simple subdued colors and good taste without resorting to anything that can give you a fucking seizure. In fact their light effects are oddly ahead of the time where you can see torches light up characters and stuff.
j) wait what
fuck idk, Souls style save system might actually work somewhat for pb game, maybe as extra difficulty option... ah who am I kidding, I am a royal f5 f9 smasher. gimme unlimited saving any day.
k) area design in PB games was always perfect narrator. decline.
L) now this is an issue.
G1 in particular is a perfect execution of how game worlds should be designed: a big chunk of a world is drawn out by a magic barrier, which actually exists and can legit fry you. It's funny, because this stuff is all over the games today, but Gothic is not just one silly game, developers based whole narrative around it. Furthermore, best loot is carried by NPCs and is given from quests and traders, so it doesn't hurt that you can go anyway. You can, ofc, break the game somewhat by going and bashing golems or whatever, and miss on cool character dialogue if you find teleporter stones too early, but it's a small price to pay for verisimilitude.
Gothics don't need invisible walls and should work on smashing any issues which come with not having them, like adding c&c and shit; I'd even remove unlockable chests too so you could rush your enclave armor if you want. It's just that kind of a game.
m) gothic area design and NPCs are specifically made to replace all the popups and tell you about the world or even how weapon combos work. Developers are missing the point and should rewatch that "why megaman is great" video.
NPC tells you find a weapon, you find pick axe then sword, fight some bird, see big castle, talk more npcs, we really need quest compass for all that?
n) gothic has blocky tomb raider places which obviously show you where you can climb, but it also has places you wouldn't have guessed you can climb, and guessing where are you supposed to climb or not, and looking at terrain, is whole reason for having 3d person/1st person instead of isometry for example. More missing the whole point of how old games work here. G1 is also so consistent and even linear that, if you just follow the main quest, you literally cannot miss ANYTHING (expect maybe book quest). Honestly it's just missing whole world design thing again.
So in the end I'd pack together stuff like invisible walls, press w to climb and other shit into megaoption "missing whole point of how Gothics world building" (which is their strongest point) and pick that as most serious issue.