Christ I cannot believe I'm going to get into this again, so I'm going to keep it short and simple. Everything already has very specific labels. Society just doesn't use them because they're seen as the default. A "regular dude" is a cis-, heterosexual-exclusive, white male who is interested in blond, 21-35 women of a certain size and from a certain background. Expressly defining these things is just a way to make it easier to determine who you are. Nobody is going to be asked to be called a "genderqueer bicurious pansexual", that's just what they are, just like a "regular dude" won't be asked to be called a "cis hetero male". They have preferences of he', her' 'they', or something else. And third, why does it matter what someone wants to be called? How does it affect your life? Do you come in contact with people so often that would prefer to be called 'they' that it negatively affects your life with trying to figure out what to say?
is the neutral mechanism you're referring to "it"? because that's a really shitty dehumanizing thing to call a person. a person is not an it. a chair is an it. a rock is an it. to turn it on the flipside, why does it chafe your ass so much to call someone by their desired label? people (especially cis- and hetero- people) love to assume that they don't need to label things because of and consequently quash the multitude of identities out there. the problem with limiting the span of identities to the simple LGBT acronym is simply that: limiting. gay-bisexual-straight simply doesn't cover the veritable rainbow of sexualities. a person is not just cis or trans; they can be anything in between. the beautiful thing about labels is that they define things for marginalized people who haven't be able to put labels on their identities. it feels great as a person of fluid sexuality to know that there are other people out there that identify out of the boxes we're told to strictly follow.
I don't see ze/zir gaining much ground in the near future. I understand that some people may be uncomfortable with gender assumptions and I wouldn't like to offend anyone if that is the case, I just don't see it entering most peoples lexicon. And to play devil's advocate, is it offensive to someone who so strongly identifies with one gender to not recognize that with "ze/zir"? Probably not, but it may be used as a counter-argument. This isn't an issue that I've heard much discussion about except for a hokey sensitivity program at my university's orientation a few years ago.