I think the real problem is that if you want fancy features like a sandboxing solution that leverages the proper way to do it (kernel cgroups, if I understood that correctly), you need to have some dependencies that reach deeper than before.

That being said, no-one is stopping enthusiasts from providing their own solution for the problems that systemd and logind solve for the GNOME project.

I always hated how all these little utilities of GNOME solved problems that were solved a long time ago and properly at that. leveraging existing solutions is definitely a good thing.

disclaimer: i really like systemd :)