Turkey should not join the European Union because it is culturally and politically not European. Entry into the EU would infuriate other member nations. Turkey is traditionally more of a middle eastern country. They are currently fighting a rebellion against Muslim Kurds and dealing with the Syrian refugee crisis, to fundamentally middle eastern problems. Turkey has no place in European politics.
The European Union has suffered some economic and political setbacks in recent years because of the addition of several nations that continue to face difficulty stabilizing their economy and political unrest. The European Union should provide these nations with adequate time to stabilize prior to allowing new nations to join. If they do not, the entire union could ultimately be threatened.