In general, I'm a big fan of Netflix. I'm usually pretty flexible about which movie I watch on a given evening and am happy to choose between what I have checked out from Netflix and what I've purchased and not yet watched. It's certainly not a case of saving money relative to other options. Rather, it's the convenience of sitting down at my computer, listing out what I want to see, and having the rest happen automagically. Over the past few years, I've become of great fan of using the Internet, auto-pay systems, etc. to relegate as many tasks as possible to the "don't have to think about" bin. But back to Netflix.
Another nice thing about Netflix is that if I run across an interesting-looking film on a Website or a Very Short List daily email (very recommended by the way), I can just pop it onto my (long) Netflix queue, for future consideration if nothing else. I was in just such a mode as I was reading an interesting article over on Filmwad called Theatrical Cuts vs Director's Cuts when I was reminded of something that has annoyed me a bit about Netflix in the past. Namely, it often offers just one version of a movie.
To take an example from the article, Alexander Revisited - The Final Cut (Two-Disc Collector's Edition) isn't available from Netflix; only an earlier, apparently out of print version is. There are counterexamples; Netflix offers both cuts of Superman II. However, in my experience, Netflix tends to have just one version of a given film.
I speculate that this decision has more to do with keeping things simple than anything else. After all, Netflix is one of the ultimate "long tail" companies; a few more copies of films popular enough to even merit new, alternative versions would, I assume, be barely a blip in Netflix' DVD inventory. Rather, my guess is that they don't want to risk confusing the average user of their site with film fan minutiae about different director cuts or alternative endings. So, for the most part, they just stock a single version. (As far as I know, Netflix also just stocks the Widescreen version even when a Fullscreen version is also available.)