As the old saying goes, there's no such thing as bad publicity. Lucas craps out another SE turd, the rabid freak-boys lap it up, post their moronic "theories" on how these changes fit into the prequels (seriously, some of these people are totally brain-dead), while the OT fans cry bloody murder, get Lucas all kinds of press, and general public laps it up and buys tons of DVDs.
Lucas is simply doing what he can to keep the Original Trilogy in the public eye, and if that means pinching out another smelly SSE 2004 loaf, then he likely feels it's worth the effort. After all, no one but the hardcore fanboys even care about the prequels anyway, and the ABSOLUTE WORST thing that could ever happen to Lucas would be for his precious Star Wars mythos to fade from the public consciousness.
So instead, he continually changes it, gets the Lucas freak-boys slobbering, has the online community humming (good and bad) and at the end of the day, makes Star Wars relevent once again. Expect this to continue with both the OT & Prequels, and for Lucas to NEVER EVER finish any of his movies.
Because he knows, once it's finished, the ride might be over.