What changed this? Christianity brining decidedly Roman attitudes.
Actually, not Christianity bringing Roman attitudes, but Romans. For the first few centuries of Christianity in Ireland and northern Great Britain, it had a distinctly Celtic flavor, including a greater degree of gender equality and married clergy. Some even believe that St. Brigid was a bishop (the evidence is not very strong in either direction). The change came when the Celts started sending missionaries to the European mainland and they came into some conflict with Rome because they did things differently. It was at that point that Rome tightened control over the Celtic church and brought them in line with the Roman way of doing things.
If the human brain were so simple that we could understand it, we would be so simple we couldn't.