Dunno, and I can only guess it's because Adobe doesn't want to do so for some reason.
I
do know that the Palm reflow app worked -- I used it myself, and still have the Palm-side part of it on my Treo. I can't find the file to install the MSWord part of it that did the crunching (I've looked a few times), and it probably wouldn't work with current revs of Word anyway.