True. I can understand leaving a few things open for interpretation. Like...did they all die in the original plane crash and was the Island just some shared life-after-death experience and none of it really happened? That's fine, since it gives people something to think about and argue over.
But all of the actual details and components to the story could (should) have been answered.
One of the main reasons why so many people loved the show and watched every episode was for the quest for answers. Every week, we felt closer and closer to The Truth. But in the end, nothing. Which IMHO was just a slap in the face to all of the loyal fans.