> Culturally, it is hard not feel detached when Germans themselves seem uninterested in cultural aspects that are normally a reason to want to learn a language (literature, films, etc).

I rather disagree:

Many German movies that are produced don't fit my taste (the reasons are a little bit off-topic), and there exist quite a few Germans who think similarly. I could come up with a list of German movies that I like, but this is something that would take a little bit of thinking/effort.

On the other hand, in my experience/observation/bubble many Germans are quite interested in German literature. I could very easily come up with dozens of books of German authors that I like (of course, such a list would be strongly biased by my own taste).

Thus I would claim that (native German) literature is much more deeply ingrained in German culture than (native German) movies, and I am really surprised that you seem to live in a strange bubble where nobody in it seems to be interested in reading belletristic books.