The Old Problem: We have only three third-person singular pronouns. 'They' covers third-person plural for every gender, but is explicitly supposed to be plural. For singular, we have 'he' (masculine), 'she' (feminine), and 'it' (non-gender). For someone of unknown gender, or unspecified gender, 'it' or 'they' are the most commonly used--but 'it' implies non-human, or rather non-person (critical distinction, if not now then at some point in the future as we become increasingly a world of sci-fi). And 'they'--I can't be the only person whose brain feels like someone went fingernails-on-blackboard when reading the pronoun 'they' being used to describe a single individual.
Both of these points have exceptions in my mind: a hive being or one with a sentient parasite might have 'they' as a more appropriate pronoun (a joined Trill in Star Trek is never so described, but it would be appropriate, unless the Trill as a species reject the pronoun as inappropriate/inaccurate. Basic rule: if a person or species rejects a certain pronoun, then don't use it, that's more polite).
'It' is an acceptable term for hermaphrodites, but again, only if the person/species considers the pronoun acceptable. I have two examples for this one: 1) In the movie 'Enemy Mine' (which I love), an individual Drac receives the pronoun 'it'. But the humans using these pronouns are at war with the Dracs, so it may be a deliberate insult, making the Dracs non-persons. Then our main character gets stranded on an uninhabited world with a Drac, who he gets to know, including learning each others' language and cultures. Then the Drac dies in childbirth, and the main character raises the baby Drac as his child--but carefully including the Drac language and culture in his upbringing. And he still uses 'it' for his child, in the rare instances he uses pronouns instead of the child's name, which tells me that he and the original Drac must have discussed it--they argue about other things, culture and the war, but they seem to have decided that 'it' is an acceptable pronoun for a singular Drac, in their sharing of language. So here I consider it acceptable.
2) In 'Guardians of the Galaxy', both volumes, Groot is a plant and almost certainly hermaphroditic. Groot could use the male pronoun, the female pronoun, or 'it'. But Groot's best and only friend at the start of the movies is Rocket, who was a lab animal and has Issues (for good reason) about being seen as non-sentient. The movies never spell out that Groot gets male pronouns because Rocket would be bothered by 'it' being applied to his best friend, but it's not an unreasonable interpretation.
The New Problem:
OK, now we (and again, here I mean the English-speaking world. I don't know if other languages have good intermediate pronouns, and I am well aware that some other cultures have a good sense of intermediate genders) come to the problem of an increasing awareness that some people are transgender. The awareness isn't a problem--the awareness is great, it's always better to know and understand a concept than to shove the concept under the rug and ignore it. But we're not linguistically equipped for the concept.
Again, 'it' is, unless a person accepts the pronoun while informed and reasonably mentally stable, a pronoun that should not be used on people.
'They' is grammatically problematic, and hurts my ears (well, my language comprehension center, actually).
So we need a new pronoun, or possibly several--the person-implying but non-gendered because we don't know the gender one we've needed all along (you hear footsteps in another room, you assume person, but you can't assume the person is 'he' or 'she' without further information, but you still might need a pronoun) is still necessary.
That alone might be enough, one indefinite-gender pronoun. On the other hand, should we have pronouns for people in transition? For their pre-transition and post-transition selves? For people who are transgendered but won't or can't transition? And what about people who are genderfluid? (And does the opposite, 'why the flip should I care about gender?' exist, and if so, what pronoun do those people get?)
We've needed at least one new pronoun in the English language for a long time. The fact that we still haven't gotten one makes me suspect that the current uses of 'xe' or 'ze' are not likely to succeed, especially since there doesn't seem to be an organized effort to get them in the English language, or even a clear consensus on which is preferred (and I'm half-convinced those are the most common because they rhyme with 'he' and 'she' but use the least common letters in our language).
But, as a reader I want that new pronoun (or possibly more than one). Language is important. Clarity is important. Could we maybe come to some sort of consensus and then organize to get the word in our dictionaries and vocabularies? (There was this one book I remember reading as a child, 'Frindle', which talks about a kid who does that. It was a children's book, not very realistic, but I seem to remember it pointed to the importance of strategy.)
[On a related note, a couple of days after I initially posted this, I watched the week's Doctor Who episode, which is a Master-focused one (most of this season is, but this one has Missy around a lot). The Doctor is talking with Bill about the Master, their complicated relationship, and after a quick discussion that yes, the Master used to be male "I think I was then, too", and of course the Time Lords are too advanced to care about silly things like gender--"so why are you called Time Lords, then?" "Shut up." (Personal guess: The Time Lords are 1) natural shapeshifters, so gender means different things for them, and 2) They were too busy being superior-species and often racist at the rest of the universe to care about internal society divisions.)
The bit about this conversation that brings me back here is that the Doctor is fluidly switching pronouns for the Master, one sentence "he" and the next "she". I suspect Gallifreyan has better gender pronouns, along with a set of regeneration-based pronouns and past/future ones, but the way this Doctor is so casually using both pronouns for the Master...it fits nicely in the bit of my head that screeches with gratuitous use of 'they'.]