Flying is still far cheaper relatively speakng than it was in the 1980's. The fact is that the numbers travelling through Cork and Dublin are very similar to the figures for 2004 when we were in a so called boom.
Of course the massive investment in the new terminal at Cork and T2 in Dublin was based on projections for massive growth which never materialised. I still think that there's too much emphasis on sun routes and that airlines should be more innovative.