I usually like to keep my characters separate in MMO's. So I can choose whether to let people or guilds know about another char, or not.
ESO doesn't have that freedom. It has a forced account name used for each guild, it adds a friend to all your chars like it or not, it puts your account in a guild not a char as the only option.
And I have times I'm talking in guild with 'account name' and then I'm in a group with 'char name' who might or might not be them - I can't tell. The guild chat uses account, the group character.
So I have to ask 'who is this' type questions.
I'd like to see more flexibility, to let the player decide between account-level or character-level connections. Maybe my cat wants to be in the cat guild and only that character.
While I'm at it, a 'hidden' option to log on would be nice. Maybe sometimes I just want to log on without alerting others like the friends list, especially when every character is visible.