In working out why societies did what they did when they did, it's useful to look at the background. In the UK and Europe, massive social-class shifting wars on the continent and in Asia in the late 1910s and again in the mid 1930s to mid 1940s. In Ireland brutal insurgency and counterinsurgency in our own streets and farmyards for a decade, followed by partition and a decade of dire poverty. The collective wish to establish a stable society was very strong. Nails that stuck out got hammered in. Which was horrible.
I don't think the stigma re illegitimacy was harder - plenty of mid-century English fiction has that lurking in the background. I think in a small country it was harder for people to move to a place where your history wasn't known without emigrating. But again - look at my links in the last post to see how the poor were treated in other countries. Also see how they treated the mentally ill.
My parents were economic migrants in the 1950s, and I grew up in lower middle class suburban England until my early teens (without any religious affiliation) and am always amazed at the attitudes and behaviors Irish people think are uniquely Irish - see the carry-on during the summer from people who were hit when they were at school. Yes, it was nasty, I remember it well, but not from Ireland.
The 1983 referendum was a disaster whatever way you cut it, but it was driven by a lay movement, not by 'the Church' (religious run hospitals never carried out abortions, but did know there were cases where non-viable pregnancies had to be ended for the health of the woman). Anyway, 40 years was long enough for me to have to argue that one.