There is no reason to believe that social norms can only change for the better, and in fact a lot of evidence that they aren't moving in a positive direction.
The US right may be overreacting to this by rolling back too many changes and throwing out the baby with the bathwater.
But that doesn't mean that conservatism in general is a bad idea. There is certainly something to be said for assessing the outcomes of a change before running many experiments in parallel without a control group.