I'm looking for a word/phrase/idiom referring to a very common phenomenon: something was born out of a requirement or restriction, but then after the requirement or restriction has been removed, the thing (or a variant of it) continues to be used, for other reasons.
Examples:
"lol" in spoken English. The written phrase "lol" was born out of the need to convey the laughing sound in writing. But now, some people use the phrase when speaking (perhaps to "signal an informal, gossipy mode of expression", as the link says).
Minecraft toys. Pixelation is used to create images on a computer screen. Minecraft-inspired physical paraphanelia have a pixelated appearance (because it's cool or whatever).
Cordless jump roping. The jump rope was invented to serve as something to jump or skip over. But now, some people prefer to jump but not jump over something. Yet, they still want to hold something in each hand and perform the rope turning motion (to give their arms a workout).
Domesticated cats. Cats were domesticated to keep mice away. But now, many people don't have a problem with mice, but they still have cats (for companionship).
Neckties. Neckties originaly had practical purposes, but now they are worn for other reasons.
The word(s) can refer to either the process of change, or the thing that goes through this process of change.
Outlive one's usefulness? Not really, because that implies that the thing no longer has any use. Vestigial function and artifact have the same shortcoming.
Become an end in itself is ballpark, but this implies that the thing has intrinsic value, whereas the things I've listed above have extrinsic, not intrinsic, value.
Maybe something like functional metamorphosis.
