I dislike it. I think it makes things more complex. And in the history of attracting users and improving their experience on a website, the answer has rarely been: "let's make things more obscure and add more option toggles." Not to mention, if you need to introduce a core piece of functionality with the option to turn it off, it's probably not the right direction.
You say that people have complained to you that comments are tiring. Isn’t that just a consequence of ‘thoughtful discussion’? Thoughtful discussion demands time, effort and the willingness to be open to and understanding of other views. And sometimes it requires you to look at yourself and reassess what you thought and believed. Sounds tiring to me. But that doesn’t mean it’s not worthwhile.
So it seems to me that by introducing this functionality, you’re trying to open up spaces where people can more casually chat without the worry of being called out. That’s fair. But the solution to that has little to do with governing the way we share posts and comments. Instead, it’s about increasing the amount of content on the site that offers those opportunities. That either has to come from the existing user base or new users. I do not believe that this experiment will address that. All it does is risk segregating an already small community.
Also, I agree with kb. My suggestion for any immediate change would 100% be the UI. I've complained about it before, but it literally goes against a lot of the most basic contemporary UX guidelines. I inject over 100 lines of custom CSS just to make this place look okay. That's not right. Those of you older than me who grew up at the beginnings of the internet may think it's not that bad. But bad web design will absolutely drive newer generation users away before they even look at the content. And if users view the design of a website negatively, that will tinge their experience of the content. I mean, default Hubski is 9pt body text and 30 words per line (though the latter differs based on display size). That is egregious. Not to mention that it defies basic web accessibility standards.