Cultural conditions have radically changed making the issues surrounding marriage and divorce far more fraught. The developed world is engaged on a huge experiment in terms of marriage and family that is actually not going so wonderfully.
The original dispensation had many similar flaws but those were at least contained. An early bad decision became a lifetime sentence. Yet a third of our population forgo community support that should be a natural basis of the marriage bond. There is no evidence that this is a good idea.
i think that the wisest course is the one we have of leaving it ti the individual conscience of a priest. Never perfect but it does allow for most to come back into communion with the church.