I haven’t seen that paper before. The ones I remember were blogposts or web pages. In fact, this may be what I was remembering: https://www.gnu.org/software/hurd/faq.html Particularly the part about what happened with the port to different microkernels.
IIRC NeXT and OSX use Mach, but they don’t use it as intended. I think they’re mostly a BSD kernel with Mach functioning as an interface to userspace.
Hurd actually used Mach as a microkernel, and moved most functionality to userspace daemons. This meant that Mach’s performance issues, at least the ones related to IPC, affected the Hurd a lot more than OSX or NeXT.
And yeah, I think developer interest was the biggest thing that held it back.
There are already libraries like clap that allow the developer to specify all their arguments including short and long variants and description strings. I think some of them will automatically generate --help based on the specified options. I could imagine a library that takes the same specifications and makes an interactive menu or a tui form out of them. It’s an interesting idea.