IRELAND: Is the mandatory 4 year period of separation unreasonable?

Here in New York it is hard to imagine that a couple would have to wait four years to get a divorce. And New York is the toughest in the country as far as proving grounds for divorce. But even here in New York, parties only need to be separated for one year in order to qualify for a divorce on the basis of separation agreement.
It was with interest that I read that in Ireland, there is a mandatory 4 year time out. Couples have to be separated for four years before they can petition the court for a divorce. Somehow, that seems like an unreasonably long period of time, doesn’t it? But prior to the 1990’s, it seems that divorce was not even legal in Ireland. I almost can’t fathom that but I believe that is correct (feel free to correct me if I’m wrong on this if you’re Irish) but it looks like before the late 90’s people couldn’t legally acquire a divorce in Ireland. So I guess it’s all relative. Now, they may be quite content to wait four years to get divorced rather than not having the option at all.