There are no bad plot devices – just overused or inappropriate ones that have been employed in a cliched manner. Hopefully you’ll be able to expand your repetoire to include the occasional prophecy within your campaign, because making foolish predictions is part of human nature, and not-so-foolish prophecies are a staple element of the fantasy genre – which means they need a little more effort to avoid the cliche.

I generally hate “prophecy” or “destiny” as a plot device in fiction and gaming. It’s not the potential for railroading that bugs me, it’s the “just because” nature of prophecy. I like to know WHY things are happening — usually driven by some human motivation, social trend, or natural phenomenon. Saying something happens because it was “destiny” is equivalent of not giving any reason at all.

The only prophecy plot lines I can think of that I like are the self-fulfilling kind. These are epitomized in Greek myth, where the child is prophesied to kill the father, so they abandon the child, only for him to grow into a hero and kill his father (the jerk). A more modern interpretation is the use of prophecy in the Harry Potter stories. Everything that happened in those books was due to people struggling to make it happen; the prophecy only acted as a sort of catalyst for the human interaction.

So I definitely shy away from prophecy in my games; it often seems like lazy and uninteresting storytelling (a cliche that has been played out one too many times). But using the techniques you outline above, prophecy could go beyond the “ho-hum, more inconsequential exposition” and become an actual interactive campaign element that the PCs can do something about.