What benefit could EIR have for the airline itself, other airlines on the route and passengers? The cities are linked quite happily as they are with low fare, reliable all jet flights. I honestly can't see what the benefit of EIR flying the route, other than a spotters logbook.
And on the subject over the last few years EI have come and gone several times on the DUB route yet U2 and BE have provided constant service for over a decade. I don't know when you were looking for but EZY/BE provide good value fares if booked in time. EIR, with its high cost base cannot compete profitably.