On why accounts were removed (and clan tags with them) as per
@GReaper :
- Authentication was in
script. It was unreliable and insecure. When connections between the game server and authentication server were lost we'd end up having to restart game servers just to get things working again - this was unacceptable and killed games.
- We couldn't release it. If another player run their own dedicated server and you connected to it, the server admin could take your session ID and use it to take your name on another server.
- The scoreboard is yet another thing done entirely in script! So even if you had connected as an authenticated user, the server owner could alter pretty much everything anyway.
- It was a nightmare for development, every developer had to get a login for their server to use the authentication server. We were also forced to be paranoid and treated every developer as a threat who could release this info.
A choice was made to enable player hosted servers, releasing map making tools and the full scripts to the game and deleting authentication. The alternative would be to keep everything locked up, have no custom maps, no scripts and official servers only.
Without a solution to those problems accounts won't come back. An unauthenticated form of clan tags however is certainly possible, after all it would just be an extra text box for the name, but it would then just become a different colour portion of your name as anyone can put anything there.