Product of an orthodox family checking in, here.
Yes, there is a huge aspect of cultural identity associated with Judaism, particularly, but not exclusively, in the orthodox adherents. Just like in Christianity, orthodox may look down on the reform movement as not true Jews - not sure how many are Scottish though. Actions like that seem to strengthen the "us and them" that persists from the Holocaust which, in turn, makes people want to hold on to their traditions even more.
Growing up, there was a lot of "being the chosen people" going around. All rather silly, but there you are.
I'm not sure, though, why the OP feels as he does. True the OT is barbaric but Christianity has as that as its background, thus it somewhat inherits some of the silliness of Judaism plus its own set of just as potty ideas.
It wasn't just the shiksa I was warned against (of course, that just makes them more attractive) pretty much anyone who was goyim was frowned upon by my "not-racist" parents. In fairness, I think they saw it more as preserving the tradition and finding "nice Jewish friends" then anything else. Perhaps too OT, but I remember the first interfaith marriage in the family and that caused huge rifts in the family despite her being a lovely person and adopting the faith. Even so, and I don't think it's definitely policy, but it still wasn't good enough and they were sent packing to the reform synagogue.
It was all rather childish but I'd given on up religion as horribly divisive, way before any of that had happened.
Disclosure. I didn't grow up in America, so this may not be the experience of many on this board.
Edited to fix some mistakes in the flow of the narrative.