I'm not against any of these projects in particular (they all solve a specific problem), however as you describe, all the recent infrastructure being pushed on desktop and servers is poorly designed and initially badly implemented. I cannot even blame the distributions, as projects such as DBus/-Kit/etc were initially just part of other, unrelated, projects that got mass adoption.

The implementation got better (actually, systemd partially got rid of many -Kit components which never truly worked, which IMHO, doing us a favor), but the design is still wonky, still poorly documented, very difficult to debug as a result and understand as a whole.

The fact that these tools rely on self-describing protocols with one single implementation without documentation also results in very tight coupling.

It's also shifting the idea of having a cli interface to perform a task to a dbus interface. Often without any documentation of the dbus interface itself to begin with (or with a crappy cli wrapper).