I've never seen that the fate of some character (not necesarily Iorveth) are not even mention when the played a key role in the previous game.
The same happened to Shani in Witcher 2, she played a major role in TW1, but until that journal note was added in the enhanced edition, she was not even mentioned in TW2. However, unlike in the case of Iorveth, I am not sure if it was ever promised that she would appear, and at least she was brought back in Hearts of Stone (which even includes a kind of simulated save import that affects a handful of dialogues). For Iorveth, it seems we get the card game, but who knows what might be in future games.
Yaevinn also got about the same treatment in W2 as Iorveth in W3, although the latter obviously resulted in much more complaints because Iorveth was made a more important character and of course he has a lot more fans.
All in all, I feel that importing a TW1 save to TW2 has a much more noticeable impact than a TW2 save import/simulation with TW3.
The save import in TW2 is also only a small amount of content, although the situation in TW3 may seem worse because the game is much larger, is open world (so the reactions to the imported choices can more easily be missed), and it would need to react to more imported choices. At least the import in the second game works decently when it comes to Siegfried's and Adda's fate, but the Scoia'tael path was again not given good treatment, I think Yaevinn is only mentioned once in a conversation with Iorveth.
I don't think wild hunt being elves is a problem (and it of course it is thing from books so there shouldn't be any problem). The problem with wild hunt and mainly Eredin is that we as players don't interact with them that much, the main antagonist, king of aen elle has 12 f***ing lines in the whole game (yes I know we have a specific thread for this).
It may be nitpicking, but Eredin actually says more than that in the game: if I counted right, he has 16 lines of "story" dialogue, 8 lines of voice set (mostly taunts), 4 combat lines that are specific to the final battle, and 6 lines of cut content (the first half of the scene where Crach is killed).
But the problem is that within the framework of the existing story in TW3, there is simply no reason for Eredin and Geralt or Ciri to talk to each other, all encounters with the Wild Hunt lead to combat. That is why most of the information about them that is important from Geralt's POV is told through dialogues with other NPCs (Avallac'h, Ciri, etc.), while lore (generally, information that lets the player understand the Wild Hunt better, but Geralt himself already knows or would not care much about) is provided in the journal, books, and other readables.
There is a similar issue with Dettlaff in Blood and Wine, although he is somewhat more talkative than Eredin, but that is partly because he is not always an enemy. Still, we learn much about him in conversations with Regis.