I'd say all racial cultures could and should be utilized more, even Human and Orc. Blizz moved past dwelling on them and now keeps throwing vampires and angels at the wall, but I think less would've been more in this case.
In no way am I saying I want another WoD with orc shit absolutely everywhere, but with some variety I think it would be cool to have proper Tauren hubs/zones for example, or nelf or forsaken stuff. Music, art, all of it. They were a big part of the game initially, and they really aren't anymore. Legion dipped its toe in at least variety and class cultures, and I think that worked great. Why not more who knows, ask the marketing department I guess.