It had its problems. If a character left or got kicked out of the guild formally, the character still had the tag on the character name. (The player who left the clan might not want to be still sporting the clan tag, and the clan might not still want them appearing to the unknowing as representing the clan.)
It would have been nice to have some very basic features, like a group of players being able to open a clan. Select a clan name. Control who can wear the clan name, and allow players who leave the clan the ability to not have to carry the clan name around anymore.
Really really basic stuff that would have smoothed things out a ton, BUT Diablo II players didn't have that option...the features just didn't exist...(remember this was still in the pre-wow Diablo II era...guilds weren't even called guilds they were called clans.)
Fast forward to D3 and....could we get just some basic minimum clan support?
It would be nice if it was done in the spirit of Diablo II, old school style. (just in game support for formation for those who want to do it, no huge real outside bonuses for joining a clan, so that no one has to if they don't want to...unlike WoW where there are certain items/perks/leveling benefits you can ONLY get from being in a guild.)
Basically just the ability to "form a clan" by purchasing a clan title some place and then the clan leader or leader(s) being able to regulate clan membership with the clan name showing up on members.
Just like it was in Diablo II in the pre-WoW days. Except now you wouldn't have to type a tag into your character name. This seems like a no-brainer since it would add extra depth to the game for players who want it, and for those who don't want it they could skip it.