As a german I really have to wonder what's wrong with our government if we continue to cozy up to Erdogan's turkey. I really don't think having turkey as a migration buffer is worth paying the price of making the european union look like a club you can buy your way into regardless of ethics. What's the use of values if we're starting to ignore them so easily?
I'm a Turkish expat (read: immigrant) working in Germany as a software engineer since 7 years. This situation disturbs me two folds: 1) For the reasons you mentioned already, 2) The power gained through this dirty game being used to suppress the already heavily weakened opposition further in my once democratic country (However, I feel more attached to Germany, to be honest).
As a fellow German, it's encouraging to hear that immigrants sometimes still feel they can identify with Germany as their new country, despite all the obvious hurdles.
My ex girlfriend's parents moved back to Turkey recently after spending pretty much their entire working lives in Germany, which got me thinking a lot. They said their primary reasons were that they could do more with their retirement money in Turkey and that the weather is nicer - but at the end of the day it means a liberal, secular couple felt like they would be better off moving into a country with a failing democracy, increasing religious fundamentalism, with a wannabe Putin in charge, as opposed to staying where they spent most of their lives.