The Jedi were overpowered and the order was broken. The galaxy was a mess (look how easily they forfeited their powers to the Emperor!) in large part because they had become so reliant on the Jedi order. The universal balance NEEDED Anakin to become Darth Vader, produce Luke/Leia and then exterminate the Jedi. Luke then brings balance to the force, redeems Vader and ultimately it is Vader that does what no Jedi could do; kills Palpatine.
I keep hearing the reason for watching out of chronological order is it would "ruin" the big surprise towards the end of episode 5, The Empire Strikes Back. At this point, is there ANYONE (even those who've never watched) who doesn't know that big surprise?
The point was if it was somebody who would have never seen or heard of star wars before. Yes, it is probably unlikely to find those people... then again, its almost as unlikely as somebody who's "never seen star wars"... so maybe its not that unlikely.
