Ireland is a fantastic place to connect between Europe and the United States. That’s one reason British Airways bought them and is bringing them into oneworld. From anywhere except London it can make good sense for BA to send connecting passengers through Dublin. It’s strategically located, makes for an easy connection and features US immigration preclearance. (BA also gets slots at London Heathrow out of the deal.)
Roundtrip business class flights originating in Dublin are pricing over the holidays for less than $1000.