I find your suggestions very welcome. I posted this same question on the aD bboards a while back, but nothing was done (though there was positive feedback).
I find myself in these same frustrations... it's just hard to read a mailbox full of bboard postings the way they are setup right now, especially after you got used to mutt's excellent threaded interface. It's hard to follow posts and it's hard to know who is answering what.
It's also hard to post a response to someone's post when that post is not the original question. I find myself having to open two browser windows: one to post the response and another to look at the response and copy/paste. Or I copy/paste from my mutt window into the browser response window.
I could make a patch to address these issues on the client side (easy). But IMHO this should be addressed on the web interface side too (harder). For example, the user should be given an option of threaded or regular interface. And you should be able to post to a certain response within a thread, instead of just the original question.