I've spent years in Western Europe: the Netherlands and elsewhere. Massive immigration from Turkey and other Muslim countries hasn't worked out so well there. Completely open immigration via EU membership would work out even less well.
Benedict XVI is correct.
Noone wants open immigration. That right could be postponed until Turkey meets certain economic criteria.
The Turks you see in Europe do not represent the Turks in Turkey. Unfortunately they have had to endure a change too rapid for them to cope with and have created a subculture to define their identities in their new countries, with rather sad results.