As a roleplayer and kind of a fashionista, I frequently find myself making temporary "dummy" characters to swipe the "starter" clothes off certain class / race combinations. For example, I have a high elf who's wearing a tauren hunter outfit with human paladin boots. I also have a gnome mage who's wearing a high elf mage robe with some warrior clothes underneath. I do this sort of thing all the time. Well, after doing this a few times, I started to think… "Gee, wouldn't it be nice if there was a vendor that sold all the class / race starting outfits?"
The way I figure it, the Alliance NPC could be in one of the many tailor shops in Stormwind City, like in the canals, and the Horde NPC could be in Magar's Cloth Goods in The Drag of Orgrimmar. The NPCs could also just be wandering around Stormwind and Orgrimmar, or if you want to be even more fun with it, there could be a neutral vendor within the Steamwheedle Cartel towns that sells all of the outfits.
The NPCs would be useful for people who like to transmog or roleplay… or just plain completionists. And… that's about it, I suppose. Eh, maybe it's not such a good idea. Still, I figured I'd mention it!
Thanks for reading!
06/18/2022 Edit:
For the curious, there are 27 unique "starter" outfits on Turtle WoW: