> Riddle me this -- why would software need any changes whatsoever for systemd, when systemd is just supposed to affect the bootup process?
I think this is part of the confusion. Systemd *can* be used to replace SysV init, and Debian has decided to do so. There are also *parts* of systemd on which applications may depend: this is what has happened with the GIMP.
I'm running KDE 14.04 on my desktop PC, and it's working with Upstart, though I have 65 scripts in /etc/init.d.
PID 1 is still called init, but I nevertheless have systemd packages installed (systemd-services and systemd-shim, plus libraries) and systemd processes running:
jonathan@Odin:~$ ps -ef | grep systemd
root 349 1 0 Oct09 ? 00:00:00 /lib/systemd/systemd-udevd --daemon
root 1335 1 0 Oct09 ? 00:00:00 /lib/systemd/systemd-logind
root 2630 1 0 Oct09 ? 00:00:00 /usr/lib/x86_64-linux-gnu/systemd-shim
So, it's not the case that "systemd is just supposed to affect the bootup process". Systemd has tentacles, and some people don't like 'em. I'm one, from what I read at the moment. Doubter, that is, not tentacle!
There's a good diagram here [wikimedia commons], which shows the full horror, et aussi en français.