> GObject has a much richer object model than what C++ provides out of the box. They could have used C++ and added the other semantics, but then you would end up with something similar to QObject in Qt and people would complain about that too.

But C compiler doesn't support GObject system. A C++ compiler obviously does support C++ types. GObject might be richer but writing GObject code is like coding in Javascript. The compiler isn't going to detect any of your type mistakes. this is not acceptable for someone who isn't familiar with GObject complexity. Qt is much much easier to work with, even for a bad C++ programmer.