FTP has been superseded by better alternatives. Anonymous FTP is replaced by HTTP. Mostly because HTTP transfer is simpler and easier to work around NATs and firewalls. (take a look at debain mirrors for example).

Authenticated FTP is just not secure enough for today's use cases. It is also replaced by S3 like file services that run over HTTP. For some reason FTP over TLS (which sounds secure enough) didn't catch on.