Im going to show some sensitivity to CupidCatt.
I think a lot of the reason that things like trans* and the like are portrayed and still reacted too negitively in society (and thats speaking as a trans person, especially after seeing studies on the internet percerption of us) is because we jump down the throats of anyone who doesnt understand a concept relating to us. I realised this a lot by talking to people at uni and how they steer clear of anyone that is trans because they dont want to get jumped on if they make a mistake or say something out of ignorence.
Its one thing when they continue to be offensive and then so it just because they can, but no leyway is every provided and I dont see that as a good thing.
The reason that people often use Alternative Gender Pronouns, from my understanding which is by no means a full understanding or an authority, everyone is going to have different views on this, is because its what matches them best.
The same as women will want to be called, or find it weird not to be called as 'her' and 'she', and by the same aspect men use and recieve 'him' and 'he', some people identify as neither male or female, and so for them, these pronouns can be as alienating and uncomfortable as someone walked up to you in the street and started talking to you and refering to you as a guy (appologies, if you would have no problem with this, im just using it as an example)
Gender is as real and importaint to many people as their biological sex is. Its not in any way a fantasy, that is to say something made up or false, its a real identity that people use to identify them as who they really are. As for medical examples, Im sure you could find something in psychological papers with trials and research being done into the concept of gender identity and how some people just dont fit. Its as natural to be in the middle of the binary as it is for some people to be born with elements of both biological sexes. You see similar things with people who forced into the binary who dont belong there, as you would if a male was being forced to live as a female or visa versa. Its traumatic and damaging.
And in the end, all referances and communication is about courtesy. There is nothing to stop you from going around calling everyone a bitch, or refering to everyone as male or female just for the sake of it, nothing at all, except for the courtesy of treating people properly and refering to them as who they really are, and for many people that is not in a gender binary. And as I said above, it can be damaging for our sense of self not to be realised, on any level, in a binary or out of one, and so its that courtesy that you are presenting to those people, the same that they present to you, although yours is yes, more straightforward.
I hope I explained that okay, Im really not in the best headspace to be typing up big complex shit but I feel that was a decent explaination first off. I may come back and add to it later.