Here's a thoughtful article in Salon on the pleasures of watching Lost. Namely that mysteries and puzzles are more fun than answers and solutions.
The real problem with Lost is that there is not an actual main character. Jack and Kate trade the role of protagonist back and forth, sometimes sharing it with Locke, but none of these characters is what you would call (in Dramatica terms) a Main Character. There isn't anyone on the island that we identify with and there isn't anyone through whose eyes we see the events unfolding. The most sympathetic character is Hurley, but again he's just a nice guy, not the main character.
For the audience, the point of the show is to solve the mystery. But there is no stand-in for us in the show; no one is actively trying to solve the mystery. In season 1 it looked like it would be Locke, as our resident Sherlock Holmes, with Boone as our Dr. Watson stand in. Locke would pursue the greater truth, and Boone would be there to ask pertinent questions.
But that never really developed. Boone was "sacrificed" to the island (not exactly what Holmes would do to Watson), and Locke went soft in the head. The rudderlessness of the show has continued ever since. Occasionally, things happen that allow us to place our hopes on Desmond or Sayid, but from one week to the next there is no consistency. The show is built around the flashbacks, which work well, but also serve to undermine our POV.
And maybe that's how they want it. The problem is that it forces the diehards to go outside the show looking for answers: The Lost Experience and Lostpedia, as well as the Bible, books referenced by the show, and the odd use of philosophers for character names. Speculation can also be part of the fun. Spinning wild scenarios in message boards to explain the clues is actually more entertaining than watching the show (the same thing happened with the Star Wars Prequels. It was more exciting speculating on the movies at Ain't It Cool News than seeing the finished products).
Speaking of speculation, here is my take on the so-called "game changer". If we do indeed flash forward, then the present action will extend to the world post-island, and the flashbacks will give us information about the island and how they escaped (this didn't work very well on "The 9" but oh well). At this point I think the writers have concluded that the pre-Island stories have been told and there isn't much left to hash out in flashbacks. Locke's backstory has been told, Sawyer's story has been resolved, we know what Kate did, we know about Jack ad nauseum, we know about Jin and Sun's marriage. It's done. To keep things moving they need an opportunity to extend the story and the only way to go is into the future.
So ultimately the game changer won't help us solve the island's mysteries, but it will provide the writer's with a convenient way to keep the show going. After tonight, they'll have 48 hours to show us why Jack wants Kate to go back to the island.