Well in general I don't understand why people want to know who's online. This is a game and not the office where your boss wants to be sure you're at your working station. And as you said his makes it easier which is a big difference for me. And I'm sure not everyone knows about the /who thing.
@Herodite I do hope the option to opt out is there
A lot of things have been asked by players and I just find it disappointing that we get one of the rather useless suggestions and not those that would actually improve the game. For instance players have been be asking for a scout notification pretty much since I've started playing (4 years ago I think...) and still nothing....