Maybe they simply see no value in keeping their modifications to qt to themselves and value in up streaming it ensuring they no longer have to maintain the code. This makes a lot of sense they are in the business of providing world class software not gui frameworks.
I am not sure if it's still this way, but I think at least some versions of the Qt Commercial License disallowed you from having user scripting in your application - or at least, exposing Qt APIs to user scripting. So no bindings like PySide or PyQt and the like could be used.
