While Ireland has the full right to decide its fate as a nation it's my opinion that Europe would do well to unify as quickly and efficiently as possible. The EU states are going to be woefully unprepared to meet challenges head-on or effectively if this sort of nationalistic bickering, isolationism, paranoia, and elite power mongering continues. (I blame the EU elites: ministers, economic powers, functionaries..etc..just as much if not more than the general public in the stalling of a fully-functioning true European Union).
With global economic and environmental crisis looming, an ever aggressive Russia, a potentially aggressive China, a loose-cannon U.S. (I am a U.S. citizen), and the threat of Fundamentalist Islamic insurrection I don't think it is in the people of Ireland's best interest to keep the E.U. from becoming a potent international power in its own right.
France, Germany, Ireland, Britain, Poland..etc...etc...cannot compete economically without each other, they cannot compete militarily, and they cannot progress scientifically, environmentally, and socially without each other's help.
Without the combined efforts of all Europeans the E.U. member states are likely to fall behind the U.S., India, China, Russia, and Brazil as economic, military, social, cultural, and scientific powers. The more cogent and stream-lined the E.U. governing body becomes the more powerful and protected the individual E.U. citizen becomes.