Notice the commonality? launchd launches services, possibly on a schedule.
And so does systemd. The other stuff is handled by separate daemons that are part of the overall systemd project. See? Separate processes! That means it's not tightly coupled at all!
Personally, I feel that systemd is a shitfest -- so bad I switched back to slackware from Arch, being more than willing to sacrifice bleeding-edge distro releases and dependency management just to avoid it -- and that the unix way is how things should be developed. It's been a while since I've really been on top of Mac OS X internals, but if what you say is true they're doing a much better job of remaining modular and loosely coupled than Lennart has been.
But the CADT hivemind has declared the traditional Unix model obsolete. They tend to do a lot of throwing out babies with the bathwater, then rationalize it by saying obviously they were children no one wanted, and aren't we overpopulated enough as it is. I don't think Lennart is particularly innovative in this regard; he learned the game from the GNOME team. When the rationale for your black hole in my /usr/lib is called "Let's Make Unix Not Suck", you know you're a special breed of arrogant.