Content in DOA6 is pretty sparse in general, what is there is concentrated on the girls, especially the most popular ones. The existence of quest mode and in-game currency gives me some hope that they will release more free costumes and customization items later, otherwise quest mode and the currency will be useless pretty quick. It would've been a huge waste of time developing and implementing these.
If that does does not happen we'll have to wait for DOA6 Ultimate, it will give us more of all that is missing rigth now: More customization items, more costumes, more stages, more intro and victory poses...