This is a particularly interesting way to handle things from a lore perspective, giving lore-minded players plenty to think about in relation to the game's events. If players choose a Dalish elf, then, the city elf origin still occurs, and characters involved with that storyline can be encountered later on. One feature worth noting is that it's strongly implied throughout the story of Dragon Age: Origins that each background story still happens regardless of whether that particular character is chosen as the game's protagonist.
Related: Dragon Age: Which Game In The Franchise To Start With & Why