@Ironclad I don't believe that is an "official" series description. Statements from the raw site and the Amazon page for the first volume give this:
Raws: はじめてのアメリカ、はじめての共同生活。ふたりでなら、何だって楽しい。この作品はエッセイではなく、フィクションです。
English: My first time in America, and my first time living together with someone else. If it's us two, anything will become enjoyable. This is not an essay, it is a work of fiction.
Amazon: ルームメイトはサウジアラビアの女の子!?初めてのアメリカ、イスラム文化、ひとつ屋根の下で繰り広げられる魅惑の異文化交流ライフ
English: My roommate is a Saudi Arabian girl!? My first time in America, encountering Islamic culture, and our life living under the same roof while fascinating cultural exchanges take place.
So yeah, the Amazon page does mention Nada's nationality, but the cultural aspect is highlighted more. This manga is about two people living together (even just the challenges that come from co-habitation and a new country) and the cultural trivia that arises from everyday interactions. True, they don't touch as much on more serious issues but this is meant to be fun. While America is a mix of lots of cultures and peoples, you're much less likely to find someone from Saudi Arabia in Japan than you are in the US. Do keep in mind that this wasn't written for American audiences, it was just translated into English. And yes, things become outdated and there's not much you can do about that. This isn't like a blog where if something shifts you can write a new post or update that entry. This isn't meant to be an essay, either. It's fiction. I see your points about objectifying these girls into their nationalities, and I'll admit you have that.