Waterford. Former Platform 3 & 4 is still a through road to the port, with only the former through tracks removed. It would have to be used by trains to the new station, making the cliff arguement invalid.Both Dublin stations are probably appropriate in size given the nature of the Irish Rail network though.
Waterford is as a result of the rockfall from the cliff face some time ago. A new station is to be built with two platforms further east along the river.
Platform 6 could have been re-instated.
There seems to be a general trend in created cheap options in Ireland. Look at Rosslare Europort, Kilkenny or Tralee for example.