Tentative ex-Muslim here, but also hates labels.
I don't know what I am but I'm definitely not 'Muslim' and my parents are, so that technically makes me an apostate.
I too have a problem with labels - but unfortunately it the Muslims and Islam who state that one can never leave Islam - once 'born a muslim' always a mulsim... Unfortunately the only way to highlight this situation and hopefully to help the people who what to leave, it makes sense (at the moment at least - I'm optimistic) to have this lable of 'ex-muslim' to show that there are those of us who have choosen freely to leave Islam.