In BG1 it's canon to get called a "whelp" even if you'd chosen gray hair, just as you'll be called "Pup" by your Cousland father regardless of choosing an older skin texture or such. I admit I got irked by it, even expressed that on the forum, but there were some who enjoyed being called "Pup." It was never a big issue for me since it wouldn't exactly be bad to be young, after all. I learned to just tolerate it with a smirk, and my reactions to the irksomeness were similar to how I end up teasing my friends. It's just not that serious.
It's not a game-breaking issue with origins. There's an inherent cognitive dissonance in it obviously, but so is choosing a dark skin when the Couslands/Broscas/Aeducans were light skinned. So would making a dark-skinned origin in DA4 in which you could make a white guy. But no one is clamoring for fewer options, are they? Intent on preventing anyone from making a dark/medium/light-skinned character or an older character? A number of players on this thread said they made older folks and enjoyed the game without a hitch. Is it awkward for the narrative? Only for head-canon perhaps. But getting the character we want sorta overrides that sort of "problem." Otherwise it's nice to be able to make a broad range of characters regardless of canon and just roll with it. It's easier on head-canon to make an older- or whatever- Cadash since one never meets one's family, so that the family could also be similar, but it's also less easy to head-canon any Cadash because it's so vague and subject to revisionism as the game progresses and reveals specifics about one's origin the player doesn't know at game start. I read somewhere (never tested it) that in DA2 they actually scripted the Hawke family to have the same skin-color as the choice made at the CC. Sounds cool, but it's unnecessary. DA2 still works regardless.
I see no reason why origins are assumed to be impossible any longer. Even if origins in DAO were exclusively about introducing new players to Thedas (and clearly they're not given that each origin is different), there will still be new DA players for DA4. There's nothing given about a DA4 that contradistinguishes it on origins-negating grounds from DAO, and there's plenty of new Thedosian identities that haven't yet been explored- and even identities that already have been introduced- particularly the Dalish- which could nevertheless be reintroduced with a new dynamic or with compelling new narrative specifics. It's just a pre-story, immersed in whatever lore is applicable. Even if they weren't to delve into a lore-heavy background, origins are still an entirely viable game mechanic that has a tremendous amount of potential for storytelling and game immersion.