If gimp pulls in systemd libs then a bug should be filed there. There is no technical requirement it needs to be that way according to the gnome folks.
During that "lengthly consultation process", nearly all of the for systemd was based on the advantages that systemd, as an init system, offer over competing init systems. In the months since Debian committed to systemd, Poettering has been increasingly vocal that he wants systemd to be more than an init system. That is why there is a renewed call for debate.
This is what I mean by reading things for yourself. I've been reading about his plans but you are mistaking the systemd init system with the overall collections of things he is working on. It's not as if the high speed DHCP daemon he has just written will end up in PID 1. His proposals so far is that there will be more optional daemons that either work better and at some point in the future I wouldn't be shocked if there were to be a debate over whether his addons should replace existing daemons but we aren't there yet.