But it is so hard for people to give reviews. People seem to give good review when are they are very pissed off or very happy. Later seems to be a very rare case.
Any product or service will have occasional customers who are either unreasonable or have bad luck. If you have a lot of bad reviews, then as a prospective customer you want to see if all of them fall under the two categories or whether there is a pattern that is relevant to you.
It seems to me that a review database works fine even when all the reviews are bad, and the only regulation it really needs is an effort to prevent one single individual with a vendetta from overwhelming it.