Several people commented and here's the overwhelming consensus:
It's poor etiquette for an author to request a change in a review. The review is the reviewer's opinion. So unless there's an error in the review (i.e. the book's name is wrong, a link is incorrect), it is generally considered poor form to request a change. Hurtful as a poor review can be, many authors believe it is part of our job as an author to take the good with the bad.
Many years ago when I reviewed books for one particular review site (I don't even remember which one now), an author was very unhappy with the first review so I was asked to do a review also in the hopes that I would give the book a better review. Unfortunately, I came upon a couple stumbling blocks with the book that I had to comment upon, so my opinion wasn't appreciated by the author either.
Honestly, I hate to give a poor review so I look for the positive points of the story to highlight. As an author who has had my feelings hurt from less than stellar reviews, and at least one downright bitchy one that did not seem to be done in the light of constructive criticism, I really don't want to hurt anyone else.
Simultaneously, however, the reader is depending on me as the reviewer, to give my honest opinion (By the way, I was completely bored by The Amazing Spiderman 2 and couldn't wait for the show to end. However, I very much liked the Gwen and Aunt May characters.) so I have a duty to help them choose a book they will hopefully enjoy.
And you know, I've been curious about books that received a very negative review and I bought the book to see if I agreed. Sometimes I did, but not always. A negative review won't kill an author, even if it stings for awhile. When it comes to movies, I often disagree with the critic's opinion. Many of my favorite movies have 2 star ratings. I'll never understand how The Rocketeer rates a mere 2 stars.
What do you think?