I would much rather have my VNs torn down and destroyed by critics than never commented upon at all. I would also much rather have a truthfully harsh review than one that's too sugar-coated to even matter. Giving too gentle reviews lowers the standards for visual novels, while giving harsher reviews raises them. This is all plain and obvious, but a nice observation is that we have two polar opposites here: really nice, and really cruel. And there are two message boards which I have posted Detective Butler on and received such criticism from.
Needless to say, I found the harsher criticism more helpful. It told me what I was doing wrong and why. Perhaps it stems from the anonymity of the board -- are people too afraid to give harsh reviews on boards where you have an identity? Or is it because of the heavy moderation which prevents such criticisms from being made?
"If you have nothing nice to say, don't say anything at all" is a phrase I have heard since childhood and I cannot disagree more with it. Saying nothing when you have a problem only perpetuates the problem; it subtly acknowledges that you DO NOT HAVE a problem and that everything is fine, which leads to failures in communication. And from my experience thus far as a VN-dev, communication means everything (both concerning VNs and IRL).
Enforcing such a policy only leads to people believing in something which is not true, a delusion. But, unfortunately, sometimes criticism can be so difficult to hear that it tears you apart, and you just want to give up. If you always hear harsh criticisms, no matter how hard you try, then wouldn't you just want to stop trying? Either that, or ignore the criticisms, but that's like closing your eyes and saying "if I can't see you, you can't see me!"
What is MY opinion on this conundrum? Have close friends harshly review your project. Whether it's a VN or not, a friend will be someone who will know you well enough to phrase the criticism in such a way that it is both truthfully harsh yet not painful to hear. One might hear "this chapter is really boring" or "what this character is doing doesn't make sense" -- softer criticisms will brush them aside, but harsher ones will want to burn you alive for making such amateur mistakes. But a close friend, in theory, should be able to explain why it doesn't work, and how to go about fixing it -- for they are the reader, just like anyone else, but will neither be afraid to tell you of its problems nor too condemning for the mistakes you may have made. What matters is that, by the time of release, you have effectively "killed" all the elephants in the room -- the things which soft criticisms skirt around and harsh criticisms make as their target.