I'm against having a figurehead who is privileged by right of birth.

So does that mean that anyone could be a President of the UK, wherever they were born and therefore whatever nationality. As such we are all 'privileged by right of birth'.  I would also rather have a head of state who was apolitical, and therefore not in any way related to a political party, than one who has to run for power every few months.  As such, the current monarchical system is perfect.