I also look at it as the international conditions being far different between the signing of the Good Friday Agreement and now.
Brexit created the trilemma which hasn't been solved. The choice of whether to be in the EU is now a choice for which country to be in.
Ireland has seen a great improvement economically in the past generation. Choosing Ireland doesn't mean choosing poverty. Also, as you said, Ireland's government is far less Catholic than a generation ago.
The UK has also become a shit show. The economic performance of non-London Britain has fallen considerably. Politics has gone from stable PM's to them changing far more frequently. The UK can't afford to be the international power it used to be; it may not be able to afford to subsidize Northern Ireland to the ability it does now.
Joining Ireland has so many pluses that staying in the UK no longer has.