Gentlemen,
Many of you are losing sight of the fact that it is called "The Open Championship" and it is a british event run by the R&A. British is not English, do not get the two confused.
Great Britain is made up of Scotland, England, Wales and Northern Ireland. That would make all courses in the south, including those listed (Rosses Point, K club, Old Head, Lahinch, Ballybunion etc) ineligible to host such an event.
As someone rightly posted, the only time the event has ever been played outside of Scotland and England is when they travelled to my home course at Royal Portrush in 1951, a tournament won by Max Faulkener. Fred Daly, who was a member at Portrush, won the 1947 Open Championship at Hoylake.
I have heard much whispering about bringing the Open Championship back to Northern Ireland, but quite honestly the infrastructure is just not sufficient for todays crowds. They have built more hotels in and around Portrush, the course has implemented some new tees and has the ability to go back further on a few more holes, but I'm not sure it will ever return to Irish shores in my lifetime.
As for RCD, again, I think the accommodations aren't there for the crowds. Both courses are worthy of an Open Championship, but I can't see it happening. There are no other courses, in my opinion anyway, that are suitable and formidable enough to test the best in the world in Northern Ireland. Wales is weak too, so what do you have left - Scotland and England, with most happening in Scotland.
My .02