Sure, that's a reasonable question.
1- The typesetting would have to be redone and that's a lot of work.
2- We'd have to download the raws all over again.
3- And this is probably the most important - there is nothing important in the extra data in the widescreen show. You can tell they knew to keep all the important stuff in the center of the frame so it really does nothing to the visual experience.
4- If we're going to redo it in 16:9, I'd rather just use the DVDs.
I hope that explains it! ^^;
-Tofu