Think about what you're asking: this thing uses a high-end server board with a bunch of exotic specs. Those things take time to design, validate, and test — don't forget that reliability under sustained load is a hard requirement in that market — so adding extra chips isn't done on a whim. Then you have to ask how many people are using this for something where the performance hit of using WiFi is acceptable — it has two 10Gb ethernet ports so you can get an idea for the kind of usage they're targeting.