I'm using "mystical" in a rather specialized sense, actually. What I mean is that postmodernist texts seem to eschew straightforward arguments - instead they use rhetorical and poetical patterns in a functional way, to inspire a specific mental stance in the reader. This mental stance might be quite simply described as "emptying the teacup", i.e. questioning and letting go of the "cached thoughts" which comprise one's current understanding of reality and culture. This mental stance happens to be remarkably useful in textual criticism and social science, where one often has to come to terms with (and perhaps reconstruct, at least partially) cultures which are far apart from one's own, so that a "filled cup" would be a significant hindrance.

Oh, and yes, I had quite a bit of trouble with trying to understand the Beaudrillard quote, although I did grok the gist of it, and I also got the similarity wrt. the Nietzsche one. But I'd say that grammar is clearer in Nietzsche's quote, and even his rhetoric seems more direct and to the point here.