Let me be clear: the real issue is not administration, because that can be replaced by PowerShell and other scripting languages. It is thousands and thousands of Installer packages and setup deployments that are using VBscript internally. I want to be clear that VBscript is one of the recommended ways to handle these capabilities and natively supported with Windows Installer. The custom actions for these installer packages need access to the installer session handle, so VBscript engine cannot run out of process and PowerShell cannot be used. It also needs to be bound to the current Windows Installer execution phase (CLIENT (non elevated)/SERVER (elevated) mode). For Windows Installer, this mechanism is buried internally inside msiexec.exe - so there is no way for anyone besides Microsoft to change that. Whatever mechanism you propose would have to require a DLL interface that mimics existing and fully support COM/ActiveX. Since the installer can run under the current user with normal permissions or elevated and can run under the Windows Installer SYSTEM service account, it's not straightforward to partition these with an out-of-process host using an in-process DLL proxy, while maintaining separation of access.
Additionally, there's other setup and deployment programs outside of Windows Installer (MSI) technology that use direct self-hosting for VBscript. This would all have to be refactored as well for any setup EXE bootstrappers. In many cases, there is no clear alternative to their existing technology stack, so those programs would have to be completely rewritten from the ground up.
Python is not part of native Windows deployments so that would not be good to make as a dependency.