Nice selective statistics m8.
Yes the population of Youghal with it transport options has not changed much.
However the east Cork area has absolutely mushroomed over the last 50 years.
Carringtwohill and Midleton being the two obvious examples but the whole area beyond as well. In fact the only reason it hasn't been even bigger growth is the lack of a railline and no bypass on villages killing the commute by road option.
However a train line would make Youghal a viable commuter hub and would also grow the villages of Mogeely and Killeagh.
It's not an either or situation. There are over 150000 people immigrating into Ireland yearly looking for housing now. Cork is rapidly expanding. We can develop the north Cork line as well.
In 20 years the problems will be worse and the solutions more difficult.
To quote a movie.