namely that, they originally went around openly, but that the Orcs targetted
them (on thir masters' orders) and the Avari mocked them persistently. So
the Dwarves did what they normally do in the face of hostility and contempt:
they clammed up.
I think the Dwarvish women probably went abroad more often than is "officially"
stated, but that your average Elf or human just didn't penetreate their
disguise.
And the line about marrying pretty whom they please and refusing any husband if
they can't have the one they want (in the teeth of the Khazad's endangered
species status), says to me that female dwarves were at least as stubborn as
the men, and probably did pretty much what they
pleased.