Okay so no doubt someone has said this but I haven't read every blog this season so here's the idea. I feel like the flash sideways is the epilogue of the show. After they mop up all the conflict the flash sideways happens, and it's the "happily ever after" or "what happened to..." part of the story. It wouldn't make much sense to make an episode where everything plays out nicely with these rather domestic if parallel issues. We need mystery and conflict but for everyone to be happy, but in the end we want to know how it all works out. Instead of a boring couple of post climatic episodes or story arcs we get them while the conflict itself plays out. I mean there is bound to be some twist to it but everyone/some losties is/are getting their happy ending.
Ben chooses Alex over personal power, seems happy
Jack is a good dad and seems to be able to let go a bit, letting dad go, not drinking anymore... (more to come)
Sayid gets to have Nadia live, even if he's still a bad dude (more to come)
Sawyer... no idea yet
Hurley is lucky and even happier go lucky (more to come)
John has a father figure, Helen and is dealing with his disability which may expand to getting fixed by Jack or not but... (more to come)
Kate... Okay I don't know but it looks like she didn't kill her dad and her name is still Austen after her step-dad (more to come)
The season isn't over so it can't explain everything but seems like a good wrap-up method. I'm not married to this idea or anything but it just seems that the mythology will work itself out and this is the ending or close to the ending, which makes me happy. Now if they can just explain the damn time paradoxes and loops and where the island went when the losties moved through time (given that the on island losties moved through time, the others stayed, but O6 whatched it fall into the water)and every other loose end then I can call it a masterpiece tell my kids its the greatest thing ever and begin my PhD thesis on the show.