Agreed on most of your points... PowerShell is by far the most powerful shell I've ever worked with on any platform... that said, I don't like it. It's very verbose.
As a JS guy, these days most of my scripts run via node/iojs and are as platform agnostic as possible. More and more I know it only needs to run in linux, or is guiding dockerization. Even then, bash scripts tend to be easier to reason about.
Actually, I did do a bit of JScript WSH scripts back in the day, well before PowerShell was an option even. IT works relatively well... I even shoved some initial logic into a few of my node scripts for windows that would, if run from WSH relaunch themselves in node.
The biggest issue with JScript in general is probably the lack of open options for certain classes of COM controls, that and COM collections are a beast (the enumeration wrapper you need in JScript is horrible). JScript was my preference just the same back with Classic ASP scripts. Could re-use my logic client and server-side, which usually worked out pretty well... though almost everybody used VBScript, which usually meant in a project both engines were loaded on the server. The other issue was runtime initialization for every request meant you were somewhat limited, though for a couple hundred users on a system at once around 1999-2002, it wasn't bad.
As a JS guy, these days most of my scripts run via node/iojs and are as platform agnostic as possible. More and more I know it only needs to run in linux, or is guiding dockerization. Even then, bash scripts tend to be easier to reason about.