That’s what I don’t get. Why? Why is it important? The only mechanical difference between a half elf and an elf is a couple of proficiencies. That’s it.
As it stands, you flat out cannot play your half dwarf.
Ignoring racial ASIs, which I am perfectly happy to have jettisoned:
The '14 elf and '14 half-elf statblocks share Fey Ancestry and Darkvision.
The Half-elf additionally has a couple of skill proficiencies via Skill Versatility.
The Elf, by contrast, has Trance, Keen Senses, and everything that comes from their subrace (High/Wood/Dark Elf) choice.
You seem to be getting hung up on me wanting Skill Versatility and that not being a significant enough thing to worry about from your perspective, but that's only half the equation - it's also that I don't want to be forced to pick up Trance, et al. in the exchange. I want to have a blend of species traits, not all of one or all of the other.
And again, this doesn't apply just to Khoravar. Any mixed ancestry character under the "Pick a Parent" ruleset is by definition locking themselves into a mechanical kit prescribed to half of their heritage at best - they get nothing from the rest. If Skill Versatility still feels too lackluster of a trait to argue over in regards to Khoravar, we can have a discussion over making it something more impactful, but this binary "choose X or Y" methodology is something that just doesn't work for me.
This may be a lengthy tangent, but hear me out for a bit... Maybe it'll give you a bit of insight into part of why I find Khoravar compelling.
For a few years now, I've been brainstorming a massive Savage Tide Eberron conversion project (spoilers, by the way), mixing together the Savage Tide AP from Dungeon Magazine with a bunch of Pathfinder APs and other adventure modules (honestly, it's way too massive to actually attempt to run and more of a writing exercise at this point) and one of the first things I had to do was figure out how to covert the AP's big bad, Demogorgon. When I think about these sorts of things, I start with narrative and theme and leave mechanics as a secondary concern, so this isn't so much a matter of how to build a unique "Eberron Demogorgon" statblock, but rather how to reshape the character of Demogorgon to make him fit into my conceptualization of the setting.
Eberron has demon lord equivalents, but they're split into a "planar" camp and a "native" camp, depending on whether they are creatures born of one of Eberron's planes (and thus intrinsically tied to that plane's themes - war, fire, etc.) or they are born of Khyber, the Dragon Below (fiendish powers native to the Material Plane), and while a case could probably be made for Demogorgon to be planar (probably from Lamannia, the "primal wilderness" plane), I've generally viewed him as fitting the "native outsider" archetype better in this use case, particularly with his overarching plot in the STAP being so Material Plane focused.
Problem is, many of the most powerful "native fiends" in Eberron are magically imprisoned through the Draconic Prophecy and generally only able to subtly influence events except through the actions of their underlings, and Demogorgon would definitely be dangerous enough in both schemes and personal might that Eberron's heavy hitters (the dragons of Argonnessen, in particular) would have an active interest in stopping him - and if a small army of great wyrms with epic level class features are dealing with him, what need is there for the PCs? So instead, perhaps Demogorgon's current active state is somehow the best they could accomplish? Perhaps he is imprisoned, but found or created a loophole that gives him more freedom to act than usual and the dragons are more willing to leave him only partly bound than take the risk of him fully escaping captivity while they try to repair his bindings?
At the same time, Demogorgon as he is classically portrayed is very much a Great Wheel/Planescape/Greyhawk/FR villain, and while I want to port Savage Tide over to Eberron, I don't just want to straight up transplant a Planescape demon lord into Eberron and say "done". So I started brainstorming ideas on how to alter Demogorgon to make a more explicitly "Eberron" version of him, cutting him down to his core themes and imagery - savage beasts, jungles, the ocean, mandrills, undeath, duality. I also read up some ideas others have proposed for alternate versions of Demogorgon, one of particular note being that rather than just having two minds that were at odds with each other, what if he was literally divided between two bodies as well. And together, that line of thought brought me to the elves of Aerenal - a culture obsessed with death, undeath, and necromantic magicks, who live on an island-continent largely covered with jungles and originally hail from the also heavily jungled Xen'drik, who have a picture in the original Eberron Campaign Setting guide with a pet mandrill sitting front and center, and who are ruled not only by their Undying Court but also by a pair of temporal leaders known as the Sibling Kings.
Skipping over some brainstorming, the general background I settled on goes like this. "Demogorgon" (gave him a new, more Eberron-ish name, but we'll keep it simple) was bound along with his peers back in the Age of Demons, imprisoned somewhere within ancient Xen'drik. He broke free some time during the Age of Giants, but knew the dragons wouldn't let him remain free for long, and so sought out the council of another of his kin, the Lurker in Shadow, an aquatic demon lord bound beneath the ocean off the coast of Xen'drik (paralleling classic Demogorgon's quasi student-mentor relationship with Dagon), and with its aid devised a way to "imprison" himself on his own terms that would both deny the dragons the use of their more certain method and give him an opening to reemerge at a more convenient point down the road.
To that end he kidnapped a random elven woman (a member of a servitor caste in one of ancient Xen'drik's giant-ruled empires) and used some terrible eldritch ritual to bind his fiendish essence into her bloodline, turning her and her future descendants into a kind of living prison that would only remain intact so long as her line survived (as while eliminating the entire branch of the family tree stemming from her would indeed kill him, native fiends can't be killed permanently, and he would simply be reborn within Khyber, unbound and at full strength) but also working in a contingency that would eventually warp the firstborn heirs of each generation of her line into avatars of his will through which he could act in the outside world. When the dragons caught up and realized what he had done, they in turn placed a curse upon the elven woman that ensured the firstborn of her line would always be "split" into twins, dividing Demogorgon's fiendish essence between them and thus breaking his ability to manifest a proper avatar through them, seemingly rendering him powerless. They then released the elven woman to return to her normal life, possibly with some memory-altering magic to keep her and anyone else from asking questions, and for tens of thousands of years, the only overt sign of her bloodline's status as the living prison for a demon lord was a bizarrely high tendency towards bearing twins.
Fast forward several millennia, and a pair of this elf's descendants become legendary leaders and heroes of the mass elven uprising that ended the Age of Giants, serving as the historical and cultural precedent that inspired the creation of the Sibling Kings down the road after the surviving elves migrated to Aerenal. Fast forward several millennia again and another pair of her descendants, seemingly next in line to be named as Aerenal's Sibling Kings (an office not based on bloodline, but routinely rotated through the various noble lines at the direction of the Undying Court) are unexpectedly denied what they see as their birthright and start a civil war over it. In an effort to better coordinate as generals across distant battlefields, they undergo a magical ritual to allow them to be in constant telepathic contact with one another, only to have the connection hijacked by the long-dormant essence of Demogorgon, which manifests as a third, partially dominant consciousness within the "network" and begins struggling to twist their methods and goals toward his ends. The elven rebels are eventually defeated, but a significant portion including their twin generals escape, fleeing into the jungles of Xen'drik and seemingly vanishing from the history books - these twin elves, having found a way to prolong their lifespans in the intervening millennia so as to enact a very long-term scheme for revenge, are now the Demogorgon active within the Savage Tide AP, their original selves having grown significantly more warped, monstrous, and divided over time but still jointly scheming to bring the civilization that scorned them to ruin, while the fiend within is manipulating both to engineer a way to fully reunite his essence and restore his true power.
But, as anyone familiar with Savage Tide knows, when it comes to antagonistic siblings, Demogorgon is hardly the primary example, which brings us to Lavinia and Vanthus Vanderboren, the PCs' early adventuring patron and the secondary villain of the AP respectively. In the original STAP, they're human and not twins, but given the themes in play and the fact that Vanthus ends up serving as an agent of Demogorgon, it feels almost negligent not to tie them in somehow. So now they're twins, and while I don't want them to be elves (as they're a noble family based out of Khorvaire rather than Aerenal and there's way more elf stuff I've worked into the outline that isn't explicitly relevant here, but would make adding even more elves to the pile seem like overkill), they still need a connection to elven lineage in order to maintain that connection to Demogorgon - thus, they're Khoravar, a mixed human-elf population block long established within Khorvaire. And that's where species mechanics enter the picture again and why I feel this whole tangent was relevant.
For what I feel are obvious reasons, the Vanderborens need something elven in their mechanics because it represents their ties to the bigger story in play. But they're also distinctly separate from it, and I have thoughts about their human heritage actually throwing a wrench into the status quo of Demogorgon's "imprisonment" - changing the proverbial "terms" under which it operates in a way that could actually make it more permanent once his current elven vessels are removed from the picture - so they also need something human in their mechanics to represent that aspect.
Which CANNOT BE DONE when all mixed ancestry is reduced to "Your character at its core is either a human or an elf. No middle ground. Deal with it."