I think the main flaw in the "adding something new" argument is, well, by adding the ability to differentiate between 'male' and 'female' dwarves, there already is one interpretation of the gender system. Here in the West, our culture treats the two as immutable opposites, with any 'deviance' seen as a bizarre exception; but to many other cultures, the decision to model only two possible sexes/genders would seem absurd.
And that's only within the human species; many creatures have more, or less genders than we do. Clownfish freely switch between the two based on circumstance; some species of lizard have no males and reproduce solely by parthenogenesis. Bees, for instance, in practice have three genders: worker, drone and queen; to assign that the worker and the queen are both the same sex, despite having very little in common, i s mostly testament to the fact that most scientists come from cultures that follow the Western binary, or have adopted it due to colonialism, globalization, etc.
Point being, genders beyond the simple 'cis man/cis woman' binary aren't 'extra' or 'superfluous'; 'male/female' isn't as default as you think, whether we're talking human culture or the animal kingdom at large.
My 'ideal' solution as such would be to simply remove references to gender altogether from sentient beings (it being sort of required in animal husbandry). Married couples could produce children or not depending on any number of factors - maybe they're sterile/infertile, maybe they simply don't feel like having kids - 'incompatible reproductive systems' would be just one of many such factors. An individual's gender as such would be open to interpretation; it's not like it has any affect on a dwarf's behaviour, abilities, or personality beyond that. I do recognize this perhaps may be a tad extreme to some but hey, the fact that I exist at all is considered extreme to some so I'm not too bothered by that.
If we're talking dwarf gender in other works, by the way, my favourite would have to be in the Glorantha setting. (King of Dragon Pass, etc.) Dwarves there were fashioned out of stone by an enormous creator god (Armok?) to maintain and preserve various massive machines, cities. etc. Each dwarf is made for a specific purpose, and is mad in such a way to reflect that. As such, they don't have 'sexes' or 'genders'; the specific 'equipment' one may have is seen as simply another way that dwarf has been specialized to their role. In DF terms, one would say a dwarf's primary identity, 'gender' even would be 'Engraver" or "Elite Macelord" or "Fishery Worker" if you're really, really unlucky.
PS. Grimlocke, no-one is calling you an evil baby-eater. Being called out on saying shitty things does not mean you are being 'attacked'. Just own up to your mistakes and apologize, maybe, or don't! I don't really care. This is sadly a very typical response and I simply do not have the energy to argue with people that don't care to listen.
