I have no grand rationale if you're speaking to the technical aspects. I found a chart of dragon morphologies and decided to see how far I could push the framework.I was talking about the out-of-game creation process, since reality-warping magic is well established in-universe I have no issue with appearances and cultures following different rules there.
If you're referring to samoyeds, that was needed as Felicia's writer wanted her to be one so I obliged. I know there is little tolerance for more races right now, so NPC need is the only thing that will drive additions, at least from me. The early introduction of mythlogicals in this way was probably a mistake on my part, yes, but it also revealed some serious bugs.Races sure are a disjointed mess though. The continuing introduction of random-ass dog breeds suggests they're intended as more of a cosmetic choice, but then you get the ones such as gryphons, yokai or dragons who grant an absurd amount of stats nothing else in the game can really compete with.
I can only speak to the races I am responsible for, but balance-wise, I used a rather primitive point total for stats in order to scale the new races to the existing ones. It seemed to work well enough at the time, however it assigned the same utility value to all stats. I am working on a more advanced 2D table with tiers under evaluation.