https://news.ycombinator.com/item?id=8648995
Dbus solves problems that the IPC methods you discussed do not. If there were a better solution, it would probably have been adopted by now.
[1] https://en.wikipedia.org/wiki/D-Bus#History_and_adoption
Linux desktops are implemented as process swarms and communication among processes is one of the central things they have to deal with.
How old is CORBA, again? And how crazy is SOAP?
"better" depends on what you are trying to do.
Of course CORBA and SOAP are considered old and horrible now, 15 years later. But currently-popular stuff is in many ways equally unsuited to coordination of local desktop processes, because it's not designed for that.