To me, this is an argument between people who value consistency between installments in their setting and people who are fine with changing things as they go. I don't care why something wasn't done in DAO. Really, I don't. The point is that that is what people had to form an idea in their minds. Intent means nothing, especially when someone can't perceive it.
Leaving skin color and race out of the equation, the reason something may not have been done originally, or the ultimate intent, does matter when we are talking about an entertainment medium limited by technology. This can be a conflict between gameplay and story mechanics.
For example, it was stated that there were limitations to having lyrium addiction be a part of the gameplay for mages and templars in DAO:
So would I. The implementation we had was that, if the addiction developed, the use of lyrium had diminishing returns. You needed more and got less. The problem we encountered, as you point out, is that mages pretty much needed to drink lyrium potions. Addiction was practically guaranteed. So there needed to be some method of dealing with the addiction without rendering it pointless, and ideally some kind of story implication...
...and you can see why it suddenly became costly. If we could come up with some other implementation that was meaningful, I'd like to see return in the future -- it was something templar characters were meant to face as well as mages, after all. Suggestions would be welcome... though perhaps in another thread.
Even in DAI, the templar PC does not have any combat limitations with regard to taking lyrium. Indeed, the templar player does not use lyrium in combat and it is only a part of the story aspect of the specialization quest.
Similarly, the qunari horn issue in DAO was also due to graphical limitations. Do recall that Sten is not the only qunari we see in the game, but also his two (or three?) comrades in the Fade if you bring him along on the Circle mission. These also do not have horns.
These technical things matter. DAO was terrible with darker skin tones, so they limited their use of them. The skin looked blotchy and the darkest shade looked purple; it was terrible. Even despite this, there are various dark-skinned NPCs sprinkled throughout DAO, they are simply less numerous than their lighter counterparts. DAO does NOT portray Ferelden as having only white people, only primarily white. DA2 had somewhat of a better color selection, but there were issues there as well. Our primary PoC followers, Isabela and Fenris, have unique skin for both face and armor, negating many of these problems.
Fast forward to DAI where we have a completely new engine that handles skin color and facial structure in an entirely new, and better, way, and we can have characters like Vivienne, Dorian, and Halward. If DAO and DA2 were to be remade with the Frostbite engine, the devs very well may have more PoC floating around.