Games from decades ago are a growing market. Remasters sell well, dedicated retro hardware sells well, and platforms for older titles have expanded. That is partly nostalgia and partly a judgement about what modern games have become.
The nostalgia part
People who played these games as children now have disposable income and want to revisit them. That is a real and predictable market and it has been served.
The judgement part
Old games are finished. They load, you play, they end. No account, no launcher, no season pass, no cosmetics shop, no patches that change the balance, no server that shuts down.
For a segment of players, that simplicity is the appeal. The games are not necessarily better; the experience of playing them is cleaner.
Design that aged well
Short games with tight mechanics. Games that respected the player’s time. Games where the challenge was the content rather than a barrier to purchasing content.
Modern games that share those properties tend to do well too, which suggests the appeal is the design rather than the era.
The preservation dimension
Commercial re-release is the best preservation available, because it keeps games legally accessible. Publishers who mine their back catalogues are, incidentally, preserving it.
The hardware
Small devices running emulators have become a category, from cheap handhelds to premium reproductions. Legally grey when the games are not licensed, and very popular.
What it tells the industry
That a market exists for finite, complete, unmonetised games. Several studios have noticed and are making new games with those properties. The retro market is, in part, a demand signal.