It doesn't make sense to me either honestly, but for now it looks like the most possible scenario. Because except this and resources issues I can't think about anything else - there is a race that is more complex than Viera in terms of haircuts, and this is Miqo'te, yet we recieve everything without issues or delays. And with resources - they could at least adapt haircuts that they add starting from 5.0 and those from Mog Station at least, yet they decided not to...
Though who knows, maybe they will just drop a big bunch of haircuts at one day - they did announce adding Shinryu weps for DNC/GNB after all. Maybe it will be the same here.