The actual reasoning was "we need to get something to make desktop guys happy. Something is better than nothing. Dbus is something". And it is a valid reasoning, right. However, it left some legacy and can now be rethought.
[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.