One aspect of writing messages and emails that I've always thought contributes to poor titles is this -- the first item we ask the user to write is the title. The title, in effect, is being written as a summary of a message which the user hasn't composed yet. This can be difficult, particularly because I often find that what I really want to write or ask becomes more clear during the process of writing it.
I suspect that if the "title" box was made to be the last thing that the user wrote, that might increase the chances of them writing a title that more accurately summarized what the message is about.
It would be a simple change to implement as an experiment. Just flip the order of the boxes and see what happens. (The title box could even be hidden until the user clicks the "preview" button, but that might be overkill.)
