"Victory? Victory, you say? Master Obi-Wan, not victory!"
I think there has to be something left for Luke et al. to fight.... otherwise we wouldn't have the ST.
(As much as Lucas liked to deny its very existence for a good 15 years or so, during the "Tragedy of Darth Vader" era, the ST has clearly existed as a concept in the overall SW storyline for much longer than it didn't.)
I was quite hostile to the idea of Jacen turning into Darth Caedus when I first heard about it, but I don't mind as much now. It was, perhaps, foreordained.
Still, I really wish they hadn't killed off Mara. Reminds me too much of the motherless families in Disney films.