How would that work for late-evaluated data? A PowerShell object doesn't have to provide all of the data up-front, and can give updated data when checked at a later date. JSON is still just text, it still needs to provide all of the data you might need up front.
Not necessarily. Text streams don't have to by default provide all possible data for the next process in the pipe. Sure, you could keep all the command line arguments you had before to make JSON output manageable, but then you have two problems rather than one.
