It does seem that 'box' carries a certain negative connotation, not just in gender issues, but looking at anything with a 'boxed in' point of view will also give you negative feelings towards it. To me, gender is a much more fluid thing, probably because I am androgyne.
I really wish there were more information available on how biology affects gender indentity because people are inclined to believe science (at least most of the time...there are some...you know who they are). Social constructs, unfortunately, are hard to change because many people are unable to understand how other people might be different from themselves and also, because some people seem to think that if they accept something like non-binary gender constructs, that it will somehow affect them personally and the world will be destroyed. Personally, life without change would drive me nuts.
It seems to me that the smaller a person's world, the less likely they are to be open to things that are different. Even if they themselves do not fit social constructs, they will force themselves to fit whichever social construct their biology demands of them. I've been watching Jesus Camp and the evangelical people in the film fit this description. They are people who have lived in the same town their whole lives, they go to the same church their parents go to, they aren't well educated (that's mostly for this film...I can't say that generally), etc. By the way, I don't want to spark a religious debate...it's just an example.

The best thing we can do as androgyne people is to be ourselves and explain when necessary. If someone can't accept it, just smile and let it go. As long as we are accepting, we will (at least eventually) be accepted.