Because you're essentially turning them into humans with modern day viewpoints.
Except that that's not required, at all. It requires effort, sure, but it's entirely possible to articulate a range of behavior that
does fundamentally differ from humanity. In my DW game, I
have intentionally made most (playable) races behaviorally equivalent, because I
wanted a world like that, but I have also included races that have...very different fundamental understandings of things. The most prominent of these are the Shi, a mostly-lost race (that probably survived somewhere in an inaccessible alternate plane). The Shi can be summarized in terms of behavior and appearance with "they are to elves what elves are to humans": gracile in the extreme, preternaturally beautiful and aesthetic, and
very alien. Their values come across as pretty Blue-and-Orange compared to human values; their magic and science were incredibly advanced, but used in bizarre ways; they delighted in creating seemingly redundant things and completely ignored other seemingly-basic avenues of thought.
It is entirely possible, if you wish to include non-human species, to do something similar. To think about what physiological differences would do--e.g. if orcs are primarily carnivorous rather than omnivorous, their population sizes and food sources are going to heavily differ from humans', and this
should have ripple-out effects on their behaviors, cultural mores, and even language. Or, as I said in a previous thread, dragonborn canonically mature very quickly and hatch from eggs, so gender stereotypes are likely to be quite different and ideas about childhood, maturity, and reproduction may be very different.
Going with "they're really just humans with a layer of latex" is
not the only option, and never has been. Why do you guys keep acting like the ONLY choices are "absolute and unbreakable monoculture," "hegemonic monoculture with explicitly and inherently rare exceptions," or "literally identical to humans in all describable ways except a funny costume"?
