i can only think of 3 reasons to have an FTP client
-YOU ARE ON LINUX
-YOU ARE ON LINUX
-YOU ARE ON LINUX
in windows you can just open FTP sites in Internet Explorer. bookmark FTP sites, download a file by right clicking and selecting "copy to folder" and upload by dragging a file into the FTP folder window.
in Linux, you just can't do that. i was at my buddy's house when he found a real cool thing for Linux, instead of just emailing me the link we decided to upload it to me through FTP (my ftp server is on windows box). we opened up Konqueror and typed in
ftp://mysite.whatever but it would give an error. we opened up Mozilla and typed in the URL, it brought up the FTP site but it would give us an error when we tried to copy a file from his puter then try to paste it in the FTP site or just drag the file into the FTP site. we download an FTP client program and by using it we were able to upload the file.
BSD would probably need one too.