That doesn't mean it's not scary when thinking about writing portable code in this environment. That's not entirely new, but the fact that so much of these details are being addressed so late in the release cycle *should* give cause for concern, especially to those of use who are still a long way from stepping up to current versions.
That sounds pretty much like an outsider view. I knew about this issue right since PEP 277 was implemented, in 2002, see issue 594001. See then issue 683592 which discusses Unicode file names returned from listdir on POSIX. Take particular notice of Guido's comment
# FWIW, I like Just's "fall back to bytestrings" aproach.
Python 3.0rc1, as released, *does* give you access to all files.
People have been going forth an back considering all the design options; the details have been addressed years ago. It's just that now, the way of addressing them is reconsidered (in the light of other things having changed along, of course).