I'm certainly not saying this made the right any less racist, but supporting explicit, legal segregation probably transitioned from simply being a loser to being a political liability around that time. Opposition to busing probably gave that a few extra years, but by the early 80s the suburbs had instituted sufficient implicit segregation that they were kind of running out of fields for that battle anyhow. Point is, hating people who aren't white never went out of style but it's probably not really providing the specific wedge issue where everybody on your side is all the way fucking in for it and the other side maybe can be scared into not fighting.

Tearing down Roe vs. Wade checks a bunch of those boxes. Abortion restrictions are, like any punishment-based policy, going to harm disportionately poor women and women who aren't white. It offers a path to keep a lot of Catholics invested in the Republican Party at a time when the right's (extraordinarily successful) anti-union effort and maybe immigration patterns are risking that. It's an electoral strategy, but an extremely longterm one given its emphasis on the court, so you're not going to be accused of breaking your promises.

Anyhow, that's my guess. Filled a rhetorical void. I'll also add, without bothering to check, that maybe their first avenue of opposition wasn't the courts but a life-begins-conception amendment of some kind and maybe it took a few years for that to peter out. The idea of amending the constitution seems laughably remote right now given how narrow our congressional majorities have been lately, but it was a more realistic part of the political landscape in the 60s so it wouldn't surprise me if pro-lifers took a little while to learn the ERA people were finding out.