Maybe the term is a reference to how these sacred places were plundered by
the Vikings and other marauders? The close association with Druids is made
in some of the Dindshenchas, especially the one about Dubad. Of course,
the monasteries and churches were also raided, so it wouldn't be an
exclusive pre-Christian naming association.
Now I'm off to the Space Center to see the sights with some out of town