Giving positive or perfect reviews for a flawed and incomplete product would only be tricking people into buying something that they will invariably dislike, and add to the already large pile of negative reviews on the net. What we want are people to be honest, give accurate reviews that accurately represent what is wrong with the product so that the devs can see what people want, and then hopefully begin fixing or adding that.
Last thing they need is more smoke being blown up their asses. They already get plenty of that here, as well as the verbal fellatio they receive every time they post 3 or more pictures of Russian huts and fences. If all they ever hear is, "OH MY GOD! Clod is perfect, you are all perfect, we love you!" Then they'll just assume they have in fact made a good game (not the case) and will just move on to making another of the same quality.
Wait!

That's already happened, and is happening again!