Was just musing a bit last night about this topic, particularly as I was working out the details for the next installment of my own Star Wars Alternate Universe campaign.
And it does seem that this is a useful approach to running a Star Wars game that a lot of GMs may overlook, particularly those who feel "boxed in" if they want to run a gaming during the time frame starting with the Clone Wars and running up to the New Jedi Order era. A lot of the "big things" that need to be done in those eras are already covered by big-name heroes, and things may feel like a foregone conclusion, which can seem frustrating to players that really want their characters to be the resident Big Damn Heroes (ain't they just?).
For those long-time listeners of the Order 66 podcast, you're probably well aware that GM Chris's flagship campaign is an Alternate Universe campaign. And after a long spell of not actively running a campaign, it inspired me to get off my duff and get back behind the GM's screen. And I must say, being able to screw with my players' expectations of certain characters has been quite fun, as well as giving them the chance to be the ones to influence galactic events on an increasing scale, as their most recent adventure did, to say nothing of introducing new NPCs, ones who could be great allies or dangerous foes depending solely upon how the heroes interact with them.
And both of our respective campaigns started off with one seemingly minor change... what if Anakin had not acted when Mace Windu made to finish of Sidious in Revenge of the Sith? I've got my own version of how those events played out, and what the repercussions have been, both the good and the bad, and I'm sure that GM Chris does as as well.
Back in 2002, Dark Horse published a series of comic books called Star Wars Infinities, each of which took the Classic Trilogy movies and spun them off in a different direction based on one simple alteration.
A New Hope - What if Luke Skywalker had missed the thermal exhaust port?
Empire Strikes Back - What if Luke Skywalker had died from exposure on Hoth?
Return of the Jedi - What if C-3PO wasn't there to translate for Jabba?
Opinions may vary on the quality of the stories and how things played out, as is par for the course for comic books these days it seems, but they each show how one change, perhaps even a seemingly insignificant one, can have major repercussions.
Years ago, during the days of the RCR version of Star Wars d20, on the Holonet Forums, a couple guys got together and created a drastic AltU set-up based on the question "What if Obi-Wan had died and Qui-Gon lived?" I didn't personally care for it, but I can't discount the amount of work they put into developing the timeline of events.
So if, as a Star Wars GM, you find yourself grasping for what could be a great hook to base a campaign upon, consider the notion of running an Alternate Universe campaign. It may take some work to develop the alternate history depending on how much time has passed between when your campaign starts and when that divergence took place, but it can also lead to a fun and rewarding campaign where your players have the chance to be the main heroes.
And as an added bonus, if one of your players is a Star Wars junkie with an encyclopedic knowledge of the Expanded Universe and gets obnoxious about how your campaign doesn't match up with the EU, you can brush off his complaints of "well that's not what obscure book reference such-and-such says" with "Hey, it's an alternate timeline, so things are different."