The real question is "What makes something age well vs what makes something age badly" and I guess that would be down to cultural standards. This doesn't just mean how PC something is, or even technological wise, but those are aspects to consider.
Instead, lets take it from gaming, as games tend to age worse over time.
Lets take Fallout 2 and New Vegas.
Both are two genres of RPG, but contain a lot of the same mechanics.
Both are, honestly kind of rough to play to a modern standard, this isn't always "dumbing down" but can be attributed to mechanics working better elsewhere or something not working.
F2 has a lot of issues, and it's hard to consider it timeless. While I wouldn't say it's aged poorly either in its writing, a lot of the mechanics are clunky.
The UI is terrible, the combat is slow and the AI is dumb as shit.
There have been times when a Companion has left me to die, leading to combat being frustrating and the whole process being slow. Games like Wasteland 2 managed to overcome this by allowing you to control companion in combat. It's a quality of life improvement, but the actual gameplay and story in Wasteland 2 isn't as engaging as Fallout 2.
Now lets take a look at New Vegas. Gameplay wise, it features many of the same issues that F3 suffers from. They are both built on the same dated engine, bugs occur all the time and gameplay wise, it isn't the most exciting shooter.
If you were looking at this game under the lens of being an FPS in 2010, it would have failed on that merit.
However, the RPG mechanics, much like with F2, save it from being lost to time.
The writing is strong, the choice and consequences give the game replay value, the skill checks add another interesting element to the game.
While New Vegas can be considered dated, it's still fondly looked back on, and will People will be able to get through its dated gameplay because everything else has aged pretty well.
F2 will get less players flited through, but again, People would look past the dated mechanics because there is something to be enjoyed there.
Now, lets take a look at movies, and one that really brings me back to a particular time is the Scary Movie franchise. It's a product of its time, and again, much like F2, People will filter through and watch it. However, that number will decrease as time wears on. People who watch it now likely watched it back then, and those who didn't watch it back then will have no interest in it now. It parodies the films of yesterday rather than being a genre parody. However, People still remember it, it's aged poorly but it exists as a product of its time.
Now lets take a look at Epic Movie, a movie which aged like death before it came out. The overreliance of movies of the day was only ever going to make it a disposable product. Back then, I could imagine someone saying it was their favourite film, but today, I doubt anyone has watched it unironically in years.
It's a film which exists for a certain time, rather than be a product of its time.
It's funny, because recently I have gone back and watched some very early Nostalgia Critic, mostly out of my own nostalgia, and while they've aged poorly, there's a certain, innocent early Youtube charm to them. It really does go back to that idea of some guy making a weird youtube video and uploading it for People to see. There is something to be said for that early kind of internet humour, and you can see how it evolved into what it is today.
There's a good video by a YTer called "Mic the Snare" who had a look back the the Black Eyed Pears album "The END" and yeah, it hasn't aged well, but it's a product of a bygone era.
Maybe something being a product of its time should be something different from "Hasn't aged well", because there's still something of value there.
I don't know if I could ever put Black Eyed Peas in the same category as Epic Movie, they hold too much for that.
