The Arab world is a big, big place.....I know you are talking about what you have observed...probably in the gulf region ..but it doesn't constitute the rule for other arabs........The most important thing for a muslim woman is to marry a muslim.....from personal experience:
-my great, great grandpa was (from Turkmenstan) was married to a Saudi.... and that was in the 1800's.....
-my grand ma ws also mixed...Morrocon/Turkish.
-my other great grandma was Egyptian/turkish
-a close friend of mine (Egyptian muslim) married an American who became muslim

And that's just me!!!

Oh...I have a cousin who married a copt christian who became muslim...(he became muslim in his teens...way before he met her).......lili.