Well, apparently, you believe no one else in the history of Congress has given any thought to it. You have to examine EVERY piece of e-mail to see if comments or questions are added to form letters, this doesn't begin to count the tens of thousands of entirely unique pieces of mail that have to be sorted individually or the letter writing campaigns which each have to be hand examined to see what was added in the margins. If you think it's easy or even technically possible, I will personally take you around to sell it to every member office. It would sell like hotcakes and not for cheap either.
So what you're saying, then, is that they are so inundated with mail that they can't handle the volume. That it's too much trouble or expense to read (let alone answer) all the mail that comes in? Seriously, it's obvious that I don't understand, so please explain to me why I should even bother writing. I am not trying to bait you. I really want to know.