Have heard it said many times that, but for the (erroneous) assumption that RoC would agree to the Annan Plan, they would not now be in the EU. And that it was a huge blunder to have allowed them in while the island was still divided.
Cyprus formally applied for accession to the European Communities in 1990, and in 1993 the European Union (officially created in 1992) considered Cyprus eligible for membership. In the statement endorsing Cyprus’ membership in the EU, the organizing stated:
Cyprus’ geographical position, the deep-lying bonds which, for two thousand years, have located the island at the very font of European culture and civilization, the intensity of the European influence apparent in the values shared by the people of Cyprus and in the conduct of the cultural, political and social life of its citizens, the wealth of its contacts of every kind with the Community, all these confer on Cyprus, beyond all doubt, its European identify and character and confirm its vocation to belong to the Community.
In 1997, the initiation for the final stages of negotiations on Cyprus’ entry into the EU began. It was announced that the EU would send a special envoy to Cyprus to monitor UN efforts there to achieve a political settlement; it was hoped that the presence of a European Union representative would further entice the Greeks and Turks to settle. Initially, it was stated that the membership of Cyprus into the EU could only take place after a political settlement had been reached. Negotiations between Greek and Turkish Cypriots were taking place; on this basis the EU announced that negotiations on Cyprus joining the EU could continue.
It was hoped that representatives of the "Turkish Republic of Northern Cyprus" would take part in negotiations on Cyprus’ membership in the EU; again, many felt that the EU pressure could help bring about a political settlement on the island. However, the EU finally announced that if no political settlement could be reached that final negotiations on entry of Cyprus into the EU would take place only with the Government of the Republic of Cyprus, since this was the only authority recognized by international law (note that Turkey was the only country that has recognized the "Turkish Republic of Northern Cyprus").
As we can see there were no pre-requisites that the Annan plan should be accepted for Cyprus to be accepted in the EU
No pre - requisites for a solution to be found before acceptance into the EU
Cyprus was accepted because it met all the criteria for joining the EU