I should have mentioned here earlier, the original thought with dbus was that nobody would use libdbus directly; KDE would use an API more or less exactly like DCOP and GNOME would use soemthing like gdbus. For that reason, libdbus was lowlevel and flexible in a way that made it annoying to use - convenience API in libdbus would have been bloat.

What actually happened is that the high-level wrappers didn't get written for a long time because libdbus was just good enough that people didn't bother to work on alternatives. So that sucked, but it does seem to have finally been sorted out and libdbus is now on the way out AIUI.