That being said, I think people are especially worried that if it's a bad change, it won't be reverted or tinkered with in a timely manner. HN has a (deserved, I think...) reputation for being unresponsive to user feedback.
This is one of the few cases where the worse a change is, the less of a voice you will have after it happens. I'm not saying it will be bad, but you can see why that would be frightening.
As I see it, trying something, even for an extended period while it totally fails, means that pg et all want to improve the level of commentary as they have seen it decline, and are taking steps to do what they can to improve it.
I don't think any community has gotten it right so far, and I am willing to surf it out, even if it means my ability to comment is curtailed a bit.
I was first attracted to HN not for the stories, though they are good, but for the extremely good commentary from people who know what they are talking about.