As one who wanted to know as soon as possible the gender of both my babies, I TOTALLY agree that knowing ahead of time has no impact on my future relationship with anybody, let alone my children! But that is just the point, for both of my pregnancies I have never felt more completely "Now", I am totally focussed on what is going on inside me, thinking about things day to day, enjoying my pregnancy even when it involves PGD and insomnia, because I am making a little person, I am a woman, I am changing, I am prob never going to have any more, etc etc. Therefore it is NOT POINTLESS for me to know the sex of my children ahead of time, if it happens that on the day of the scan it is possible to tell. I was lucky to see the bits, I guess. I definitely wouldn't have wasted any of my future "cappacino and croissant" funds on a private scan just to tell me the sex, that really would be pointless, unless I was a genetic carrier of some condition which meant I had to prepare myself to have handed on to a boy....
So, lets's just say, if you want to know, it's good to find out, and if you don't want to know, it's good to not find out. It is not good to say to anyone "Find out!" or "Don't find out!" if it makes them feel they are being bossed about. My dad doesn't want to know the sex of my baby this time, and so I haven't told him, but I am happy telling other people, as it is part of what I am thinking about.