I can understand the desire in some cases, as users quote the whole lot of a long post for little benefit.
However there are others of us who know different and strip off all the extraneous text, smileys, etc, down to one or two lines.
You can never be certain what will be the post above yours. By the time you have read the thread and then written something and transmitted, several others may have posted in the meantime on a busy thread.
Now if we were BA we would have a solution. Just charge £240 for any quote beyond 23 words