'Harshly negative' sounds like being an asshole. My question to you would be do you want to be right or effective? It can feel good to be right and stick it to someone, but how often does that lead to effective change?
You can shear a sheep many times, but you can only skin it once.
You know you're doing well, and everyone only has small improvements to suggest. Why keep digging? There's nothing bad to find. After all, you're doing well.
The SNAFU principle[1] is a joke, but it's one of the "haha, only serious" ones. It's entirely impossible to avoid the SNAFU effect altogether. So perhaps I should have said "when was the last time you rewarded a bearer of bad news with a highly desirable outcome like making staff?" In any event that was what I meant.
[1] https://www.techfak.uni-bielefeld.de/~joern/jargon/SNAFUprin...
Look, in professional setting truly being a dick - especially regarding this question - is relatively infrequent. Often someone doesn't understand that his arguments - or general actions - are off by substance (i.e., he's wrong and should be able to see and correct the mistake) or form (often he's telling not enough, assuming people will understand the way he means, and the form is such that they understand it differently than intended). Harsh criticism could be a lack of form - when the person doesn't put it in a shape somehow convenient for understanding, acceptance, analysis - or substance - when the person is wrong because either he doesn't know something, forgot something he did know... Truly being a dick professionally is to be "lazy enough" to systematically make these mistakes without taking care to fix them, or "evil enough" to do them on purpose. A decent organization has ways to hire and keep professional people, improve less professional and leave those not improving; the level of dickiness is under some control.
Sheep can be skinned once, but people aren't sheep, and power imbalance requires those wielding more of it to have the ability to grow that skin. Your question is valid and rather to the point, and I would like to learn more of the answer.