It depends on the platform and the application.
When it comes to computer hardware, an ethernet port or an optical drive were “must-have” features for the longest time… until they weren’t (users started using wi-fi and most download their media).
When it comes to operating systems, I think the file explorer is going to (eventually) have a similar fate – a feature that users must have today but will eventually fall away from heavy use (they won’t need to browse a document directory – they’ll use search or open documents through the “recent documents” feature in an app).
When it comes to a current example, I think the Print feature is something everyone “must” have, but when it comes to practical use it’s something that the bulk of users don’t need anymore. While we are far from the “paperless office” promise we heard years ago, we still print far less than we used to (and tablets are becoming a preferred “delivery mechanism” for information to many in business).