And I say this who have written them. In my defense,
- I was a much younger writer, then.
- I believed that the story demanded it. And
- I think I got away with it.
Of the above, #3 is probably the most important. Good writing is all about what you can get away with, and one of the big lessons to learn on the way to becoming a good writer is figuring out how much, and what sorts of things, you can get away with.
Usually, the answer to “how much can I get away with?” is “not nearly as much as you think.” On the other hand, sometimes your muse doesn’t leave you with any choice except to say, “what the hell” and go for it. At which point, you do your best and take the consequences as they come.
So, anyway, prologues. Not nearly as many stories need them as have them, and entirely too many failed stories – especially in the Epic, or Doorstop, Fantasy genre – start out twenty years or so before the main action, with the portentous birth of the main character, or the portentous death of somebody important to the backstory, or the portentous prophecy of some future birth, death, or general catastrophic doom. For this reason, if you find yourself feeling the urge to commence your novel with a prologue, at least stop first and ask yourself, “Can I put this same information into a flashback somewhere around chapter five? Or into a couple of paragraphs of dialogue between the Young Protagonist and his/her Wise Mentor somewhere around chapter two? Or will this section work just as well if I label it ‘Chapter One,’ and commence the next chapter with ‘Twenty years later’?”
If you can answer any one of those questions with “Yes,” then you should probably take the hint and revise your no-longer-prologue accordingly.