I think the current policy wonks holding the reins are in a "more flies with honey" state of mind when it comes to foreign policy. I mean, Cuba and Iran. The other thing is that Europe has reason to need to deal with Turkey - Syrian refugees aren't coming to the US unless they're either damn lucky or damn cosmopolitan. AND they're shooting down the Russians. I'm not as up on Turkey as I should be but I think pressuring Erdogan has Turkey ending up with somebody worse. It's like, Khatami wasn't great but boy howdy did you want him back once you were dealing with Ahmadinejad. Considering how badly Turkey wants into the EU, this might actually be a spectacle that the United States can watch and tweak from the sidelines.
Yes there's an interesting dynamic, because the European project is a direct result of Europe trying to deal with its violent, racist, despotic past. Perhaps Germany thinks that Turkey should do the same as a precondition to full membership. That seems unlikely to happen, especially since the fall of the Iron Curtain, EU has been will to let in pretty much anyone who wants in, regardless of their revisionist histories (see, e.g. Viktor Orban). Seems like at some point the EU pivoted to make the project more about access to cheap labor than about cooperation and peace (about the time the Eurozone became a thing; coincidence?).