Except Void elves have adopted a counter-culture to Blood elves, with it’s very own stylized appearance revolving their worship of the Void, much how the stylized appearance of the Blood elves revolves around their own culture.
In almost all dialogue, and quest text the Void elves reject their past before their change and this is reflected in the visual design of their hub, their clothes, weapons and structures. They mock important Helf/belf cultural aspects like the Sunwell, we see them butchering nature, and consorting with one of the most corruptive sources of magic in existence. (something I can’t imagine many nature, or light revering High elves would ever abide)
To then suddenly turn around and make them out like they’re woodsy Farstrider rangers would be completely contradictory to them in almost every capacity. Especially when we take into consideration that the original Void elves were Magisters who greatly disliked Farstriders and their old-timey “nature-loving” ways.
Alleria was never meant to reflect the Void elves visual, they were never meant to be fair skinned, or have natural hair colors, these are RP tools. These options were never meant to help them look like Alleria, it was just to further the Helf request, it was even described as “helf” customization by the devs. The Undead can’t look like Sylvanas after all, and they were never meant to. Which is why no Void elf NPC in game utilizes these RP tool customizations while Blood elves were given a Mage trainer using the helf options immediately after they were introduced.
Alleria was meant to look like a Blood elf, and the only reason her appearance is more accurate than existing Farstriders is because her model was created recently, where as most existing Farstriders were added in TBC. She was modeled after what many Blood elf players have been requesting for years.
Umbric is their leader, and ultimately the one that determines their design, culture and visuals going forward as a race. Alleria had no hand in this, as her views greatly contrast that of the Void elves, whereas despite her association with the Void continues to wear her Farstrider armor, and even worship the Sunwell. Whereas void elf voice lines show us they care very little for the Sunwell, or their culture as Blood elves.