The new motorways have brought Cork and certainly Shannon into the Dublin extended catchment area. That combined with the recession has seriously damaged the two smaller airports.
While I don't go along with the view that the DAA are conspiring to undermine Cork, the reality is that there is absolutely no incentive for them to boost traffic there as any increase is almost certainly going to be at the expense of Dublin.
In some ways it is comparable to the situation in the UK where foreign airlines stubbornly refuse to fly to Stansted, Gatwick, Luton and Birmingham due to the massive drawing power of Heathrow.
There is also the painful reality that apart from CSA and Malev for a brief period during the last decade, no European flag carrier has ever showed an interest in operating scheduled services to Cork.
Lufthansa, Iberia, Air France and SAS have probably concluded that the Market is simply too small to take on EI and FR on one of their homes bases.