I logged into TS a few hours ago, and saw beside the user-channels header, that passwords for channels aren't allowed. Why? It gives people the privacy of just talking to the people they want. It's not like it's a bad thing.
It can be somewhat bad depending on the group, as in my experience on other VoIP servers (mumble,ventrillo,etc) sometimes people will tend to only hang out in password or authenticated users only channels. Such if this were to be staff of whatever the server is ran for, it can be bad in the case others have a need to contact that person on the VoIP server.