The critical thing with ORK-DUB is that there is only one potential operator. So, if it was reintroduced, it would more than likely mean lost seats to UK regional destinations.
I'm actually surprised EI don't want to to feed transatlantic flights though. I know it would take people off ORK-LHR and ORK-AMS, so the benefit isn't what it might be, but it would still make a lot more money for them to fly a passenger across the Atlantic.