This specification was later replaced by RFC 765 (June 1980) and RFC 959 (October 1985). It's remarkable that the current version has not changed for over 25 years. There are several proposed standards that improve on RFC 959. RFC 2228 (June 1997) proposes security extensions and RFC 2428 (September 1998) adds support for IPv6 and defines a new type of passive mode.
FTP became popular since it required a minimum of handshaking, and was tolerant of temporary interruptions, making it very useful for long file transfer sessions. As alternatives became more and more easy to use though, FTP's adoption decreased. FTP is still used as an internal business solution to sharing large files. Because it so outdated, however, it is rarely used to easily allow external parties to access confidential information that is too large to send by email.
Personally, I still use FTP to update a website I maintain for a club. Other than that though, the last time I consciously used FTP – many applications still use it in the background for certain tasks – was years ago when I was trying to pirate something with my friends. FTP isn't really useful for piracy anymore and unless it's upgraded, it will die a slow death as alternatives continue to take over. Do you still use FTP, and if so, for what?