That's really useful to hear, especially from you, (presuming you're the same wbond who wrote oscrypto)! Have you written or considered writing a longer-form expansion on these experiences?
And yeah, in spite/because of all its simplisticness, ctypes really does seem to win out among those who share Python's aesthetics.
Yes, I am the author of oscrypto. Unfortunately one of my unfulfilled interests is longer-form technical writing. Trying to balance open source and family means that for now, that isn't in the cards.
I think one of the biggest benefits of ctypes is that it is part of the stdlib. Not requiring a compiler means it opens up a whole swath of users who aren't Python developers, but have Python installed. Part of the reason I'm interested in this is being heavily involved in the Sublime Text community, where every user has Python and ctypes, but requiring a C compiler and Python headers eliminates probably 99% of users.
Trying to distribute pre-compiled shared libraries was a path I went down, but gave up on. Having to compile 10 versions of the cryptography package every time a new release came around was a disaster. If you chance upon the cryptography-dev IRC channel, you'll see it is a part time job to get the package compiled reliably, and they have dedicated hardware provided by Rackspace to help them.
And yeah, in spite/because of all its simplisticness, ctypes really does seem to win out among those who share Python's aesthetics.