What Gives Role-playing Games Their Longevity?

In his latest column on western role-playing games, Rowan Kaiser ponders on the longevity of the games in the genre, many of which are still being played today a decade or two after their release. Here's a snip:
It's this combination of mechanics and narrative that makes RPGs so memorable for so long. Neither of these two components can be made obsolete. Yet despite the appeal of older role-playing games, there are still problems with blanket recommendations or treating old games in the same way as newer games. It's an unfortunate fact that, in terms of interface specifically, many of those older games are inaccessible to many people.

Planescape: Torment, for example, is probably the pinnacle of storytelling in video games, but having encouraged many people to try to play it over the years, it seems to be a coin flip whether they can deal with the quirks of the Infinity Engine or not. Much of the time I can't deal with the engine, especially given how rudimentary its combat is compared to later Infinity games like Baldur's Gate 2 (I've taken to recommending new players set the difficulty to easy, advice I need to follow myself next time I play). And Torment is relatively accessible compared to pre-1990 games, designed before the mouse was popularized as well as before computers had enough space to include critical text.

Although an older game's accessibility can occasionally surprise you, they're generally more work than a modern tutorial-heavy game with streamlined controls and clear graphics. "Nostalgia" can muddy these waters as well. Nostalgia is a difficult concept when talking about games. It can be tempting, for example, to dismiss an older or old-fashioned game that you don't understand as being only good based on nostalgia. Likewise, it's a constant worry when you discuss a game you haven't played in years: what if it's "just nostalgia" blinding you?

For this reason, I've stopped using "nostalgia" as a critical frame of reference, and starting using "fluency." Nostalgia is simply too subjective. Whereas fluency, one's ability to learn and maintain specific abilities, can be generalized. Fluency depends on willingness to learn, connection with the learning subject, and amount of time one can invest. I may try to play as many games as I can as a wide-ranging critic, but to take a few examples respectively: I'm simply not that interested in realistic flight sims (willingness); every attempt I've made to work with text adventures has failed (ability); and thanks to the need to play a variety of different games, I simply can't afford to be a multiplayer expert anymore, as a I once was when I was a World Of Warcraft raider (investment).