This is something I have been pondering and wondering for awhile, and I'd add that I have also mentioned this to BL staff and made a request for reblogging feature to be optional when comes to reviews, so I hope this is something I will see in the future.
I absolutely understand why people do reblog reviews, to share the awesomeness. But I personally strongly dislike when someone reblogs my review (no offense to anyone, this is my personal preference), although it has happened less than 5 times or so. So it is not like a huge problem for me. Other reblogs I, however, do adore.
My reasons for dislike are:
a) when a person reblogs a review, reblogged review will be added to the book page. Now, let's say you write a review and 20 people reblog it. It means book page is filled with 20 identical reviews.
b) when a person reblogs a review, as I mentioned, the reblog is added to the book page. But it shows under the blogger name of the person who reblogged the review, not under the name of the original reviewer. You actually need to open the review to see that it indeed is not the person's review but a reblogged review of someone's else.
c) reblogged review is always shown as the newest. When I did not know this, I sometimes re-posted my review after editing etc. which made my review the newest. That way the reblogged review shows as it would be the oldest (or first) review. I didn't really see this as an problem before I realized you actually have to go to the review to see that it indeed is a reblog. I figured perhaps it will cause problems. Funnily enough, after a week someone asked through other book site if I am copying reviews. Well no, I am not. It got solved after I did advice them to click the review so they can see it is a reblog of my review.
d) I am starting to think this is one way for author's to promote their faces ( I am not talking about authors reblogging reviews about their own books but random bloggers reviews of popular/less popular books) as reblogging will put their face up to the book page. This has happened to me few times.
Hilariously enough, there still is people who do not know what reblog means, and people who do not even notice if review/post/whatever is reblogged while surfing the feeds.
Thoughts? And pardon me if I explained this in a difficult way, my brain is not in English mode at the moment.