(I'm assuming you don't mean a terminal emulator, but a command-line shell when you say »unix compatible terminal«.)
The team that developed PowerShell actually wanted to do just that. They didn't, because Unix was built mostly around text files, so tools that work with text files are a good way to manage such a system. Windows however, is not, so Unix tools are a particularly poor way of managing Windows.
That's also why PowerShell treats file system, registry, WMI, etc. as first-class constructs, because it has to to be effective.
The team that developed PowerShell actually wanted to do just that. They didn't, because Unix was built mostly around text files, so tools that work with text files are a good way to manage such a system. Windows however, is not, so Unix tools are a particularly poor way of managing Windows.
That's also why PowerShell treats file system, registry, WMI, etc. as first-class constructs, because it has to to be effective.