For quite some years now there have been ecumenical talks about celebrating a common Easter among Catholics, Orthodox and Protestants. Quite frankly I think it undermines what has been discussed: mutual respect for liturgical differences between the East and West. Creating a universal date for Easter could lead to more schism.
It was over this kind of non-dogmatic issue that led to the Great Schism of 1054. The patriarch of Constantinople, Michael Cerularius, battled with the pope after Greek priests in Sicily were given the ultimatum to say Mass in Latin or have their churches shut down. Other issues raised were the Filioque clause, the use of unleavened or leavened bread for Holy Communion, and clerical celibacy. These are all non-dogmatic issues which people on both sides tried to impose on the other. I certainly would not squarely put the blame on Catholic clergy as Cerularius certainly vilified the Latin Church over the Filioque clause — which Saint Maximus the Confessor defended centuries before — and the use of unleavened bread to consecrate into the Body of Christ, not to mention there is no justification for splitting from the Church.
If the Catholic Church agrees to observe the Eastern Orthodox dating of Easter, it could lead to schism — not of Orthodox — but of Catholics who may already be disillusioned with ecumenicalism. The Second Council of Lyon and the Council of Florence both concluded with Catholic and Orthodox clergy agreeing to the legitimacy of different practices. I don’t want to sound like I’m saying that changing the dating of Easter is wrong; the dating for the celebration of festivities has changed throughout the centuries. I just do not see the reason to make a change in the hopes of reunification especially if there are much more effective ways of achieving that.