Ditto PPs, it's obviously a super personal decision that has no right or wrong answer. I'm a FTM so I can't speak from prior experience, but we're Team Green now, had our a/s about a month ago.
I never felt like I needed a sex and name to bond with the baby- I also don't necessarily feel super 'close' to the baby though. Crazy protective and always a little worried about how he/she is doing, of course, but I don't feel like I really know him or her yet. That's how I always wanted it though. I was a little afraid that finding out would give me certain preconceived expectations that were hard to shake. That might not make a whole lot of sense and I can't even really explain it... I just want to meet and get to know the baby, not my idea of the baby. We plan to go to the hospital with a short list of names for each sex and decide sometime after the birth on a final name, in case something just really seems to fit above the others.
What has helped us though with the suspense and everything is giving the LO a NN. We've been calling it 'Gus' from about week 5 (and do use 'him' and 'he' in casual passing for simplicity's sake) so we can talk about 'building Gus's crib' and so on and so forth. So even without knowing if Gus is a boy or girl, he/she has sort of taken on a role (if more or less unseen, lol) in mine and DH's everyday life and gets incorporated easily into daily conversation. We talk to our cats about being older sisters to Gus (I swear we aren't crazy...).
There are also less complicated reasons, some of which are kind of silly: we don't plan to share the name possibilities and will only announce THE name after we've put it in ink, and I feel like going green will help us sort of shuffle our feet when people want to know (twice as many options to consider as the Team Blues and Team Pinks have and all! ). I despise frills and ruffles, so if LO is a girl, I want at least a little bit of time unencumbered by the hideous things my best friend will send me to compensate for my own lack of girliness, lol.