Eh... thing is, that is an opinion -- which some share, and others don't... since everyone draws the line on things like "enough to matter" at a different spot.
The point here seems to be that some people have concerns -- regardless of other people's opinion on the validity of those concerns, it would be relatively trivial for ZOS to add an optional flag in one's account management to allow for the setting of a display name (and thus hiding one's actual login id).
They can't please everybody all of the time -- but if a simple tweak would satisfy some additional people, without making others upset (is there a valid reason why changing this would upset someone?), doesn't it make sense as something to ask for then?