AOB, they didn’t dress for tznius, they dressed for the simple reason that as a kings daughter, it is completely unacceptable to dress in anything less than modest. and when a person thinks of a princesses clothing nice, good looking (modest!) clothing comes to mind.
and, I think I would be a little bit happier if people who did NOT want to dress to impress people, would if it meant their clothes would be a little “better”.
About the arab part, (sorry) I said that the religious arab women wouldn’t dress in anything other than their shmatas so we, religious jewish women (lehavdil) are willing to dress in clothing thats not so perfect?