BruceLeeRoy said:
So thats as much as we ever know about the island right? Its a real place but its actual purpose in the role of their lives is never clarified.
It was monumentally important to their lives. As Christian said at the end, the time they spent on the Island, with those people, was the most important time of their lives. If nothing else, the crash brought together this motley crew of people and through their relationships they regained purpose in their lives. As Lindelcuse have been saying, the show was about these characters being 'lost' not so much geographically but in their own lives.
But more than that, in WTDF Jacob said "I chose you because you needed this place as much as it needed you." They needed the Island to find themselves; the Island needed a new Protector. Why? Because without a protector, the light goes out, not just on the Island but everywhere. And if we take the light in The End to be the same light (which I think is heavily implied), then putting the light out, to me, essentially means snuffing out all life, if not all of existence.
In one of the podcasts that was posted in the topic, there was a complaint that the flash-sideways being the afterlife rendered most of the rest of the show irrelevant. I couldn't disagree more. What occurred throughout the entire show is precisely what even
allowed for there to be an afterlife. Without the goings-on of the first five seasons, there wouldn't be an afterlife AKA flash-sideways.
For instance, if the Losties hadn't gone back in time, they wouldn't have detonated the bomb during the Incident. Without the bomb going off, the energy would have been uncorked and presumably would have had the same result as allowing Smokey to leave (everything ending). Also, without the bomb detonating, the Swan Hatch would never have been completed, Desmond would never have been taken down there, he never would have failed to push the button, which means the Losties would never have crashed. And without the Losties crashing, there would have been no one to replace Jacob which means Smokey would eventually leave and life (and the afterlife) would cease to exist.
Long story short, the flash-sideways truly was the culmination of the Island story arc of the entire show.
Not knowing what the Island really is kind of makes the ending bittersweet. I feel like its the real character of the show and not know what its motivations or ultimate purpose was is driving me crazy.
The Island is the Source of life, death, and rebirth (which can be interpreted as the afterlife). At the very least, it houses a unique connection to the Source. And the motivation of the Island can be viewed as self-preservation. In the end, the island (and its light) is safe from the threat of Smokey. If the Island was the cause of anything, it culminated in its own safety. In a way, Smokey might have been not have been part of the plan and everything that happened was a way for the Island (or the universe) to "course-correct," as Eloise might say.