Euan, over at the Magic Den, posted an amusing list of why memorized decks are dumb.
Judging by the comments, I'm not sure many people get the point of the article, though.
It's satire, people! The point, at least to me, is to make you think why you're using a memorized deck. Are you using it to simply stroke your own ego, or because it is making it possible to bring more amazing experiences to your audiences?
Euan's last comment is:
If you're going to use a memorized stack you might as well just start using a marked deck or a svengali deck. Or even better, a marked svengali deck with rough and smooth thrown in for good measure.