Why do you think feedback should be always constructive? Buying game for the most part is not a rational constructive decision, people do not create a math model of value of particular game against its price and determine their own tolerance levels. No, people just ~feel~ that game is desirable enough for its price or even simply impulse (emotional) buy it.
It IS a feedback, and more important - it's a most natural and thus most honest one.
And gamedev should want this type of feedback as it shows what emotions your game induce (as emotions are buying power of games) to understand where exactly planning went wrong, to learn and hopefully not make the same mistake again. And as I said before, different reaction means different things and mistakes in different parts - indiffirence is one thing, rage is another, disgust, contemp - all are different. Reaction itself is not enough as vocal minority might not represent all players, but with other metrics available to gamedev it should give a proper picture. This is why gaas games have CM that should have very thick skin and listen to community woes constantly even though its very often degrade to whinning, rage, threats of quitting and insulting. Because for gaas games it's really important to maintain understanding of their playerbase as players are their lifeblood, and loosing them means death of the game.
And rationalization of emotions in "constructive criticism" is just random bullshit 90% times. Players often have wrong ideas in their rationalization, as they lack knowledge and experience, what drives emotions and makes game good. This is why reaction alone is not enough, because players often over-react initially, but when they try it, they like it.
