Because a $3 billion-dollar net worth was not enough for Mr. George Lucas, he looked at his idiomatic money-making turnip, the Star Wars films, and said, "I think there's still some blood in there." For a more succinct answer to the question of "Why?", see this chart.
Thus, his Star Wars sextuplets will be re-released into theaters in 3D, so that we may experience the true visceral nature of moments like the Tatooine camel farting, 10-year-old Boba Fett watching his father get decapitated, and a floating-waterbubble-squid-opera. Oh Star Wars, you so crazy!
According to THR, Lucas will begin unleashing the 3D conversions one year at a time beginning with The Phantom Menace in 2012, which means you won't get to see Leia share her space crackers with Wicket in Return of the Jedi until 2017. For those too young to have seen Jedi, "share her space crackers" was literal, not an innuendo.
All snark aside, I loves me some Star Wars, and am actually in that rare camp that thinks the prequels were decent. Hell, I even own a Talking Jar Jar Binks 22" Figure Wake-Up System:
When you pull his string, he actually says "Meesa coming! Meesa coming!" (Whether my ownership of this is ironic or not is none of your concern.)
However, there was definitely a feeling of relief when 2005 rolled around and the saga came to its logical end. Instead of obsessing over the films (or writing articles about them), I now have time for more rewarding activities, like making homemade pistachio ice cream, or perpetuating conspiracy theories about 9/11. With Lucas bringing the films back to theaters for a whole new generation of indoctrination, I can feel the words of Al Pacino when he said...