Wanted: a non-hierarchical comment system. Trolls of the world, unite!
This is an interesting subject! I'm curious if it's the lack of visible nesting that errs you on the side for a flat comment structure, or if there's a more fundamental objection to the idea of nested comments.
On one hand, I really like the idea of having all discussion be "about" an initial post, whether that be the parent "topic" or a parent "comment". It gives allows for many divergent flows of conversation, all capable of being followed independently.
On the other, a flat structure potentially offers greater flexibility – if we merge the idea of "topics" and "comments" altogether. Maybe comments can have arbitrary metadata? How would the user experience for this work?