I agree with you. It's pretty obvious I came here from Reddit, probably the same TheoryofReddit post that got a lot of other people over here, and I definitely don't want this to be "just like reddit but smaller." I'd rather it be something which can scale while promoting interesting discussions. That can scale the act of having interesting discussions. From a dialectic standpoint, being able to collapse comments is essentially being able to ignore them- something which I think should be avoided. Easily silencing opinions is a bad idea, and definitely stifles longer posts while promoting zingers and one-liners. Clearly that's a bad thing- if you don't want to read interesting posts, I don't particularly want you in a community I'm in. So on that we agree. But we also need to be careful of the opposite happening- if a post has a lot of replies, it's possible that it will become the only thing people see. And that's as bad as ignoring everyone but those who responded quickly to whatever the top comment was. I think a nice middle ground would be to have reply chains with more than 4 children have their own little scrollwindow. You could scroll down to read more of that comment's replies, while being able to move past it after noting its prominence. Setting a number (4) instead of some sort of variable amount (% of total replies, maybe) isn't a great idea, but it's a start.
Okay, so a compromise. And your argument from the other side is fair, I agree that long strings can hide good content as well as encourage it. Your solution strikes me as a bit cumbersome, though I may be mis-visualizing it, but I'm sure that if mk decides it's necessary he can implement something that fits in.