The 'Dragon Age' and 'Mass Effect' series of video games has player choices -- that may not be apparent in advance -- which influence the fates of characters you bond with, and alters the ending. I have not finished a complete playthrough of any of these games, because I'm afraid that my choices will leave me with regret, and when I come back to make different choices, the novelty will be gone, and the suspense, the hopes and the fears, the genuine real-world emotions I feel wouldn't be the same.

In my case, having multiple endings to a book would definitely make my hesitation worse.

I think it's simpler than that. We don't want to miss out on a great ending by picking a suboptimal one. Endings are definitely not equal.

No, it wouldn't be a good thing. Stories are works of both art and engineering, and neither of those fields have much room for random outcomes.