"Bad graphics" as a term should only refer to graphics that are difficult to visually interpret within the game design, or graphics that are simply too bland/uninspired to look visually interesting. Metal Gear Solid 1 doesn't have "bad graphics" because I can still visually distinguish what I'm looking at and they don't interfere with gameplay. Silent Hill doesn't have bad graphics because it has interesting design.

The recent Gotham Knights game has bad graphics because despite the game's attempt at realistic, compelling visuals, they come up very flat and weak in comparison to previous Batman Arkham games. Fortnite has bad graphics because it looks like a bland corporate cartoon mess.

Maybe some younger folk have a hard time interpreting what things in early 3D graphics are supposed to be? Or they have a harder time understanding the visual clues? I'd think the main difference would be gameplay design quirks in older games, not just the graphics, but things like figuring out where you're supposed to go without things like quest trackers or compass markers. Quality of life stuff like that seems like a bigger distinction between older and modern games than just visuals.