Well, that is a bit of a philosophical question, no?
Let's see, human and elven interaction over the millenia has been characterized by conflict and opression with elves being, generally, on the losing side.
This has, of course, lead to the collapse of original elven culture and identity and the suffering of untold generations with no prospect of it changing anytime soon.
Even at the genetic level, the two races appead determined to destroy each other since human/elven pairings lead to human offspring which further contributes to the extinction of elves as a whole. Which, of course, leads to people like Vaughan existing.
Knowing all of this, it seems elves and humans both would be far happier and safer if the other group plain and simply was very far away. Thus, are they meant to share a living space? I think not.
If you take this arguement to it's logical extreme, no one should share living space. Every sentient race, real or fictional, competes for land and resources. As far as seperating Elves and Humans, I have to ask: and then what? Exploration and expansionism would eventually put everyone right back where they started. Exterminating the Elves altogether? To satisfy some player God Mode fetish*? Forgetting the moral, or even practical considerations of such an option, what could it possibly bring to the table from a narrative standpoint? Do you really think Bioware would write two completely separate Theodosian campaigns, with and without Elves, thus straining already limited resources and angering a large portion of the fanbase? This isn't like the Geth, Quarians, or Krogan in Mass Effect, this a Player Race**. It's possible that the lands beyond Thedas do not contain Elves in significant number, but that is years down the line. Besides, even if this is the case, in all likelyhood Elves will still be a Player option as "The Explorer" or some such.
Sorry, but to me this just sounds like "I don't want fantasy in my fantasy roleplaying game".
*Count me among those becoming leary of the growing Player Entitlement movement. I agree that the Player Character should reflect whatever personality the player chooses for them, and they be completely competent and proactive. I do not however, equate competance with mind raping NPCs into following their every whim or warping time and space just to get a preferred outcome.
**While I'll admit that my knowledge of Mass Effect: Andromeda is sketchy at best, I know we will have at least one Krogan NPC, squadmate or no. Yes, Krogan are long lived, and it's possible there could more than a few Quarians who accompanied the Andromedan expedition while still giving the illusion that their races are more or less extinct. I also find it extremely hard to believe Bioware will be able honor the wildly devergent ME3 endings without coming up with an alternate canon.