I walked out of the theater from Star Wars III with my dad with whom I had a memorably different reaction than I did. "The movie wasn't fun like the old ones," my dad said. I couldn't argue that the dialogue was wooden and that is the general consensus. The lines have more gravity behind them than the innocent serial adventure that was the original Star Wars.
But then again, the Star Wars prequels weren't exactly serial adventures and this might have also been the source of their undoing in terms of connecting to the large base of viewers that the original trilogy did*. The Star Wars prequels were enjoyable, more than anything else, for those moments where we go, "Oooohhhh, so that's how it happened." To the extent that Star Wars is a pseudo-real universe**, this is like going back into the history books and reliving those historic events in a way that we can never actually do with real history. I might even consider it to be a more authentic experience, considering you can never truly recreate the Wild West or the Civil War except for a documentary but you can create the story before Star Wars IV with absolute authenticity, considering it exists only within the mind of the filmmaker who creates it. As mentioned before, this appeal has to do with one having to have extreme familiarity and interest in wanting to explore the Star Wars experience to further depths. Now, I don't know the exact numbers but we all know there is a significant following of Star Wars devotees who are very, very into the Star Wars phenomenon and the fan base extends beyond those who dress up in costumes and go to conventions.
When thinking about it more, it struck me that these elements that are what drives the prequels, catering to a fan base who wants to know the story behind the story, are also becoming an ever-increasing part of the present-day film experience with the advent of DVDs. With the extra features that come with DVD's, people who weren't necessarily film buffs before might be converted into them simply because learning things about what went behind the making of the movie they are watching becomes so much more readily available to them and is presented as entertainment. Movies are no longer texts that are limited to their final cut that appears on the screen. They become more plastic and your knowledge of that text changes as you chose immerse yourself into it more. That choice also makes the relationship between the viewer and the text interactive and as film watchers and it adds to the other outlets with which we, as film watchers, can immerse ourselves in these stories. The previous outlets were books that were relegated to the sci-fi section of the bookstore and only appeal to the hard core Star Wars (or Star Trek, for that matter) fans, but we can immerse ourselves in a more accessible way.
So to conclude, DVDs have helped to create the appeal of prequels ranging from Star Wars I-III to Batman Begins, or even stories that might fill-in-the-gap between previous stories like Superman Returns.
*One might argue that because Star Wars III became the 7th highest grossing film of all time (now 8th, displaced by Pirates II) and Star Wars I became the 4th highest grossing film of all time (now 5th, displaced by Shrek 2), that these films were seen be everyone. By "connecting," I'm speaking of number of satisfied film goers, which I don't believe Star Wars was able to do on the whole.
** I place myself in the casual fan category