Quality discussion isn't supposed to always feel good. Nor is it a bad thing when what you've expressed is heavily analyzed and perhaps contested.
It's really no different than physical exercise. Yes, it can be painful in the short term, but over time it allows adaptation that increases strength and robustness.
As a former long-time Slashdot reader, the progressively-worse site designs were far, far more disruptive and harmful than any changes in the quality of the discussion might have been.
Their beta site was what made me stop visiting earlier this year. The fact that such an unusable design could seriously be considered in the first place was partly responsible. Their lack of action when confronted with lots of very legitimate concern regarding the beta site was also responsible.
Maybe things have changed since then. But I wouldn't know for sure, having not bothered to go back there.
The debate will still be there either way, will it not? It's probably preferable to base such discussion on a correct log of the events, rather than speculation and unsubstantiated allegations.
Sometimes the only reasonable and legitimate response to certain ideas and claims is to dismiss them. It's much the same for negativity. Sometimes a negative response is the best one.
Highly sanitized, politically correct, feel-good discussion is pretty much pointless to engage in. The best value and insight often comes from asking the hard questions and pointing out flaws that are painful to acknowledge.
It might not feel pleasant all of the time, and it might not make people happy, but engaging in discussion in a way that some people may consider "negative" or "dismissive" often gets the best results for everyone involved.
It's really no different than physical exercise. Yes, it can be painful in the short term, but over time it allows adaptation that increases strength and robustness.