Why are there so little reviews?

Ok, you decide to buy the latest gizmo in town. You really want to know how good is your product. You go to the product site and ooze over the nice little high quality pictures and features 'marketed' to you. Then you realize , this might just be the tip of the iceberg. So being smart , you go to some www.xxxxypssl.com and read reviews about your product and make up your mind whether to buy the product or not. Simple isn't it? Now let us look at an interesting statistic and see how bad/good is this behavior. There were 'at least' 10 Million copies of Harry Potter and Half blood prince sold , but Amazon has just over 3500 reviews for this book( the book apparently was one of the top review generating product). The product usage to product review ratio is abysmally low!

Do you still think this sample which is not even 0.000001 % of the total population is good enough to base your decision on?

Studies have shown that reviews normally tend to be 'j' shaped , skewed more towards positive reviews. How dependable are these reviews then?

Adding to these , there are paid reviews which further raises questions on the intentions of review writers

Having stated why reviews might not be a nice starting point , what baffles me is why there are so little reviews even for a product which sells in millions. People always have something to say about a product in real life (good/bad), but most of them don't materialize online!

Now, consider this. You have a problem , say your latest PDA phone loses charge very often. You submit your problem to Google and Bingo (no pun intended) there is a solution to your problem in some www.xxxtechxxforum.com (given by geekwhoitis who already has 3B replies to his/her name). Here is a product which has some defects and people report (can we call this a review) it , while in the former case it goes unreported by majority!

Is there a difference between these two instances of consumer behavior? My guess is over and above all social reasons , there is a personal satisfaction of getting things done or in other words the IMPACT your actions create and how it directly affects you (does it solve 'your' problem or show 'you' as a significant contributor?).

Can we increase the number of reviews to a product by showing what IMPACT it would create? Is there really an IMPACT to the person who gives the review? Are firms taking note and more importantly 'act' on these reviews which are free market insights?