What I'd really like is for a mail client to find a way to make inline responses simple and intuitive, to the point that your average user would think to do it.

Am I the only one that doesn't like inline responses? Most of the time they feel awkward to me. I do use them when responding email from a couple of co-workers that are inlining fans; and when I need to add a point-by-point reply to some technical email.

The rest of the time, however, I top-post proudly. Feels like the closest thing to writing a reply letter.

Isn't that more of just a preference thing? I mean, I suppose Gmail/your mail client of choice could simply show the quoted previous email in the reply email box without any added spaces before, but I think most people would just hit enter a few times before typing (or go to the bottom as they prefer).