Of course Aer Lingus regard ORK as a "genuine base", it's certainly more "genuine" than the likes of LGW and BFS. Year after year ORK keeps the core routes and new or additional routes are tried, some stay, more do not.
Personally, I think Aer Lingus at ORK have their hands slightly tied by just having the ATRs and the A320 (assuming the 319s remain in Belfast for the time being). Something E190 size would probably work quite well, I think there are probably a number of routes that the A320 is too much for and the ATR is either to small or does not have enough range. We are already seeing that, to a certain extent with BHX and MAN, with the addition of 3 daily flights on certain days. Similarly out of DUB there are routes which would benefit. In particular I suspect that growth on the Regional side will be slowed by a lack of profitable places to send the ATR fleet in the mid morning, afternoon and to a lesser extent in the evening. There are only so many places you can fly in the UK and Northern France. A jet might just help, allowing EI to open up some longer, thinner routes which could depart in the second bank of flights and return in time for the evening bank of flights to the UK.
EI have clearly taken the decision that they want to keep the mainline fleet all-airbus, so maybe the need is not as acute as one would guess.