Now, now, needn't be snide. For the work I do, and the environments I work in, Powershell does not satisfy my requirements, that's all. It's not worth writing applications in a language, no matter how powerful, that isn't available for most of the machines I need to run the app on.
When Powershell is available on the machines I use and administer daily, I'll reassess its usefulness to me. Microsoft could great speed the arrival of that day by simply porting it to (say) BSD Unix or Linux themselves and releasing the resulting code; it's not like they can't afford the resources required, and they would be heroes as well.
I'm sure Powershell is the cat's meow in all-Windows shops. Neither I nor my company nor my clients are all-Windows operations. The days of "Any serious business has to be a Microsoft shop" are long over.
Which tool is more useful, which tool is better.... "Depends on what you're doing."
OS-X has six major flavors of the Bourne and Csh families of Unix shells already, any of which are at least as capable as Powershell