Top-posting is used a lot among those I correspond with at work, and most of them apparently use Lotus Notes which doesn't seem to handle mail threads either, so they keep accumulating top-posted top-posted top-posted mails. The net result, anyway, is that after a while it's totally impossible to have the faintest idea about what, exactly, the person is commenting about.

Top-posting is evil, and not even allowed on some of the more important mailing lists I'm on. So I'm all in favour of getting this fixed, either as default or as, at the least, a configurable option. Vote done.