Because there is no default clothes, because if there is default clothes, the warrior type will only wear the highest defense, and the mage type will only wear the robe. So if you set the default clothes, you will often give her other clothes and wear the default clothes.

Manufacturers don't set default clothes at all. . . . (I just did-,-)

You can ask her to bring a few pieces of equipment, and she will wear it (soldiers still only wear the highest defense ... unless you have a special dressing MOD).