To me the secret sauce behind powershell is the .NET infrastructure, which allows much more runtime introspection than the usual compiled programming languages, allowing a lot of flexibility without being too wonky. Unfortunately the Windows team seemed to not be on board with this vision, and thus it cannot achieve its full potential. The objective-c runtime may have been a good alternative here too, but I don't think Apple is encouraging its use anymore (and Objective-C is not the right language for that, neither is AppleScript imo).

You can also access COM from PowerShell, which basically opens up a lot of the Windows world to it.

And both .NET and COM and the object-oriented history of Windows is probably also why PowerShell will never really feel "at home" on UNIX platforms, for better or worse.