The main purpose of Waterford-Mallow since about 1906 was Rosslare Boat traffic, especially the Rosslare Express. This is from another era, and there is not much point in wasting energy on nostalgia for a beautiful line.
Maybe Goods has a point about the cost of automated crossings. It appears that CCTV monitored and fully signalled 4-barrier crossings are the standard. There are very widely used automatic half-barrier crossings which should be perfectly OK for a fraction of the cost (unless of course you cant trust Irish drivers going round them in pursuit of a Darwin award)