Re: all the prefix arguments do the same thing

[Richard Stallman]

    Well, how about let's say one doesn't want to replace the region, nor
    put it in a separate buffer, but instead insert the output above or below
    the region?

    Currently any prefix argument means "replace".   Do you think just
    maybe you could make some certain prefix arguments do what I want?

I think that would be creeping featurism.  You can duplicate the region
before you run M-| and get the results you want.