Earlier quoted context omitted.
How about the non-modifiable hidden system partition? Inability to create directories under / That alone has stopped me moving my Macs to the latest OS after testing.
I'm genuinely curious: why do you want to create new directories at the root level? Is this something you're just used to doing and it breaks your customary way of working? Is it a "general principle" thing (which I suspect is a lot of the objection the HN crowd really has at the root, no pun intended)? I've been using OS X-based Macs since 2002 and used Linux and FreeBSD for a decade before that, and I don't recall…
Why not? It's his system, he should be able to do whatever he likes. On most Linux I can rm -rf / all day long and nobody cares. What's the problem with creating root level directories?