I was thinking this as well. The bash version which is included with OS X is really old[0]. They refuse to ship any software which is licensed under GPLv3. It makes me wonder if they will reverse on that stance?
Homebrew also breaks with every major OS X release. It would be really nice to get some 1st party support on a package manager.
I feel like Apple does the bare minimum in this area to stay POSIX compliant. I would really like to see them feel some pressure here.
[0] https://www.reddit.com/r/bash/comments/393oqv/why_is_the_ver...