Just wondering why suddenly everyone is in agreement FTP should go away ..
FTP has a standard way to list directories. Using HTTP that way would require you to either have a well-known index file or parse HTML looking for links which don't return text/html responses.
The downside is that FTP still has issues with firewalls – I had to troubleshoot that earlier this month, actually – and is another service to maintain if you are already running an HTTP server.
In the case of either single-file downloads or something like a Linux package manager, the URLs are well known so directory listings are irrelevant. HTTP has a number of good options for CDNs and caching, so if you care about performance or reliability that's a turn-key service.
In the cases where directory listings were more valuable, people usually wanted a richer UI than just a file listing, too, and there are tons of options for that in the web world.
Also there was a day before dependency resolving automatic downloading GPG verifying distribution clients. I was there... Say you needed to roll back (or security upgrade) some software, you'd quite possibly go to a FTP site thats trusted, download some tar.gz or tar.z or shar archive that was trusted, make, make install, plus or minus some configuration of course. You can't do that via http in 1990 while telnet'd into a server, the http infrastructure and commands and servers hadn't been invented yet.
Its also important to point out that at least some of us were fooling around with unix and FTP (and FTP to non-unix OS, I vaguely remember some TOPS20 server in the late 80s early 90s... simtel20?) before http ever existed. So naturally there were a lot of tools and processes and experience getting things done with FTP when HTTP arrived.
Decent FTP client CLIs were extremely advanced. Not exactly "wget someurl" and hope for the best LOL. Automatic login with differing accounts per site, text mode graphs and stats as downloads commence, tab completion, local help command functionality, multi-connection support... Mirrored and often lead the developments in modem/BBS download functionality (think like Zmodem on Telix not kermit)
Its sort of like those "how could you have thought using telnet was a good idea compared to ssh?" Well, I had 15 years of unix experience before OpenSSH was deployable, so we had a lot of telnet experience...
I'm a nostalgic kind of guy, but FTP is terrible through firewalls and nowadays, bittorrent or http are just as well.