It's funny as well, because 65kg on one women and 65kg on another, even when they're the same height, can be very different, look very different, and probably most importantly, feel very different for each woman. So while 65kg night be ideal for someone whose weight is distributed evenly across her body, 65kg on a really top heavy woman may not be ideal.
So true PZ - that website where you can see women of a certain height and weight compared is really interesting for that - shows exactly those differences. Forgotten the name of it though!