I think that would be the overwhelming reason that even if there was any discussion on changing the electoral system in Ireland, no one would suggest changing to first past the post. It would be to change to some other kind of PR, although even that issue is not very live. The last referendum we had on the electoral system was in 1968, and no one has really ever proposed going to first past the post since then.
On July 26th, 2016. See this statement in context.