All of your questions are easily answered by reading the link provided at the top of the article:
Why does the desktop care who's booted it up?
The Init System "We don't care. It doesn't affect us."
logind Allows KDE to provide user-switching features.
Device Management Allows KDE to have access to your mouse and keyboard without root access and without random applications being able to sniff your keystrokes.
Inhibitor Locks Allows KDE to react to notifications like "the system is about to go down" and delay until a condition is met (example: delay a suspend until the lock screen is displayed and all your desktop windows are hidden behind the lock screen).
timedated and Friends Allows KDE to set time and date without root; allows KDE apps to be notified if time and date gets changed. (KDE currently runs a daemon just to watch for time and date changes, and they would like to get rid of this daemon and simplify their code.)
User Units If KDE takes advantage of the "units" in systemd, then when any part of KDE crashes or hangs, systemd will restart the misbehaving part.
that implies they won't work on *BSD at all. Right?
"Projects like [SystemBSD] bring the interfaces we need to BSD and as it gets more stable we should be able to start distributing features."
So really, choice is being taken away clear across the board. Either that or I'm missing something really big which implies systemd is not a strict dependency.
I encourage you to read the whole article and see what big things you are missing.
I don't know about you, but when I read that article I didn't think "Man those KDE guys are idiots, why would they want any of that." It all makes sense to me.
It's easier for me to believe that SystemD has some merit than to believe that all the Debian core developers are idiots, plus all the Ubuntu developers, and now all the KDE developers and for that matter the Gnome developers.
My biggest concerns with systemd are the monoculture of it all, so projects like UselessD and SystemBSD sound great to me. Force the SystemD guys to document and justify everything, and provide alternatives.