In terms of 3D art, I'd have to have mods or some seriously strong recommendations to play anything trying to be "realistic" prior to 2002. Even back then I thought it looked like crap.

In terms of 2D art, I'd say CGA.

Although way before that, lack of affordances and quality of life features would be pissing me off. I played Dragon Age: Origins back in the day (but also gave up on it about 3/4ths the way through), but trying to play it again recently I gave up almost immediately due to the weird interface they hadn't figured out yet :D

almoat no VR games have photo-realistic graphics, due to the limitations of the hardwares. especially when you consider the Quest games, as the Quest is very limited. The only games I can think about as more or less photo realitic right now is Half-Life: Alyx and Kayak VR: Mirage. Most of the popular VR ttitles, like Beat Saber and Pistol Whip, are quite abstract and stylised.

If I were to push it, I'd say late 80s. But I only played a few of those, so a more realistic cutoff would be 1990-91.

I'd say ASCII graphics and no graphics (text based) for me. Other than that I'll roll with almost everything graphics-wise in old games. Inconvenient controls/interface are much more likely to scare me off.

The key here is "old games". I have almost no patience for new games trying to be "retro" in their looks, unless they have a really great art-style and execution.

Pure text, ANSI, or EGA graphics are fine for me.
But I just don't want to play early 3D polygon games, except flight simulators.

I misspoke. Sorry.

What I meant to say was I dislike photo-realism in games and VR. Why VR? Like photo-realism it breaks the "wall" that I like between game and reality.

Controls and gameplay. I don't care if its not pretty (unless its literally impossible to tell what's going on), but if the controls are too clunky and counterintuitive I just drop it.

It's a variety of factors, really, but I rarely go back to play NES and Master System games. I usually go back for quick bouts of SNES, Mega Drive, PS1, and Saturn games, besides a bunch of arcades from the same era.

On the PC site of things, controls are what count the most, followed by gameplay and graphics, though I tend to consider ease of getting the damn game working as well.

I see nothing wrong with your two examples.
However: that's probably because I played these games (and others like them).

And that's also where I draw my personal line when it comes to playing games with old graphics, sounds, steering, etc.

I am much more willing to put up with any of those, if I have played a certain game already when it was still new.

Where I probably differ vastly from other people, is that I usually don't say:
"well, I played "game A" from this (graphics/sound) era and this genre before, therefore I will also enjoy "Game B" from the same (graphics/sound) era and genre, despite me never having played "game B" before."

Having played a certain game in the past already, really makes a huge difference for me, when it comes to my personal "tolerance" level, in regard to old graphics/sound/steering.

So - I guess, as an answer to your question, I could say, I don't really have a "cutoff point" when it comes to old graphics/sounds/steerings (heck, I played old text adventures, with nothing but an (often enough: shitty) parser)...but that doesn't mean that I'm willing today, to play everything, that was ever done with those old graphics/sounds/steerings.

Most early 2000s XBox/PS1/2 3D games look like crap, there are only a few exceptions that I play. I mean ... Tomb Raider is a classic but it really hasn't aged well. At least is supports 3Dfx GLide, so wrappers can be used to improve it a little.

As for 2D I am more tolerant. I love the look of many games from the 16 Bit era.

However, by now I am really fed up with that pixel art look, that many modern games have.
I love what 16Bit machines starting with the Amiga were able to produce (it took years until Sega and Nintendo were able to catch up).
Back then in the 80s and 90s the devs tried to make their games look as good as possible, usually restricted by memory and schedules, not so much by costs. They used as many colors as they were able, parallax scrolling, drew the figures in a way to simulate shadow effect, they used deform functions to simulate 3D effects,
The graphic chips had special functions to bring even more colors to the screen, for example by changing the pallette while drawing the image. Since (S)VGA it has become a lot easier to produce great colors. But what we get these days is a flat look with only a few colors and characters being composed by one or max. two rectangles and some lines for the limbs. That just doesn't do it for me anymore. It was fun and interesting for a while, but that train has passed.
I don't expect high res graphics from every game, but at least we could match the late 90s.

Edit: Audio: I hate it, when retro games use early NES and the megadrive for music reference, they were just the worst.
Once more I have to mention the Amiga (4 hardware wave channels, it was possible to premix sounds on the CPU, resulting in the famous 7 channels sound of Turrican2), but also the Atari ST and even a SNES could sound good, if you got the right musician / programmer to work on it.

I also dislike it when the gameplay breaks that wall, as well.

For example:
* Pokemon Gold and Silver introduced a mechanic where it would be day or night in game depending on whether it's day or night IRL. (This can be a problem for people who would rather sleep at certain times, but those times happen to be the only time you can catch a specific Pokemon, for example. Or, for that matter, the two Eeveelutions added in this generation evolve depending on whether it's day or night.)
* Final Fantasy 3 DS, in order to unlock in-game content, requires using mognet to send messages to other copies of the game, something that became much harder with the shutdown of the console's internet service. Fortunately, other ports of the 3D remake changed it so that this is no longer necessary.
* StarTropics does this for one puzzle in chapter 4, which is annoyingly well after a save point, so if you don't have the trinket needed for the solution (and can't just look it up), you have to play the entire chapter from the beginning. (The game auto-saves at the start of every action stage, but chapter 4 has none.)
* One non-video game that is a bad example is the one called "the game", which commits what I consider a really big sin (if such a thing can be said to exist); the rules say that everyone is playing it, and in fact, according to the game, you likely have to announce now that you lost it.

Graphics and sound don't really have cut-offs for me. It's all about the experience: controls and input, menus and play. Readability (or rather lack of) has a big impact for me.

Example: Loop Hero tried really hard to make me avoid the game. Terrible text, low-contrast text, unrecognizable icons. It's nothing to do with the palette itself, but how they used it.

Thing is, I actually like the NES sound when it comes to music. It helps, in particular, that the NES is simply not capable of producing the sounds that give me headaches.

On the other hand, the sega genesis sound chip (what you're calling "megadrive", I assume) I don't like that much. I don't like its much harsher tones, and the sounds it seems to be best at are the ones that tend to give me headaches.

There's also the fact that music quality can vary from game to game, depending on how well (or poorly) the developers understand the sound chip.

For example, with the Phantasy Star series:
* PS1: (On the Sega Master System) The music here is decent, though there's the issue that the SMS sound chip sounds like a less capable version of the NES sound chip.
* PS2: The music just doesn't do anything for me.
* PS3: Some of the music is wonderfully composed. Unfortunately, most of it poorly utilizes the sound chop. For example, the title screen music has what sound like loud banging on bells, with a quiet melody that you can't really hear, and the theme for that one Layan town has a nice round that you can't really hear the second part of. (On the other hand, the music for the first part of the final dungeon actually works rather well.)
* PS4: This game actually makes good use of the sound chip, and aside from the occasional track that could give me headaches, actually works rather well. In particular, the first world map's overworld theme manages to work quite well, and is one of the rare times that a Sega Genesis game's music has a woodwind-like sound. (Well, the fantasia game on the Genesis, while it may not be the best game, does somewhat imitate a woodwind in one of its tracks, but it's not the instrument that most people think of when they hear the term "woodwind".)

There's also issues when the colors are too similar, like with red versus green koopas in Super Mario Bros. on the NES. (I consider this an accessibility issue, and there are other games with this sort of issue, like that one Bomberman falling block puzzle game (except the Virtual Boy version) and Guacamelee!.)

Anything with teal as it main colour is dead to me.