Noted. I think what's interesting to me is that Lost started to have the Harry Potter effect on me. In the first six books, they're mostly at Hogwarts. Now, Hogwarts is a great setting, dumb name aside, full of history and nice backgrounds and whatnot. However, by the sixth book you could almost start to sense Rowling's desire to take the characters elsewhere: it opens in the city of London, Harry and Dumbledore leave Hogwarts to journey to a subterranean cave, and so on. And in the final book, they don't even go to Hogwarts until the climax and that was just awesome because it was great to see the characters somewhere else besides that fucking castle.
I felt the same about Lost, but to a much lesser extent. I think what I liked the most about the last season was that the characters, by that point, were like island vets-- nothing scared them or really tripped them out anymore. It's not a new place to them. That sense of mystery was gone, except for things like the lighthouse and the light cave. I think this might be where you're coming from. In the earlier seasons, there were these frequent hikes they went on into the unknown and that brought about a sense of mystery and even creepiness. One of my absolute favorite segments of the entire show is at the end of the first season when they travel into what they only know as the "Dark Territory." Giacchino's corny, not-good-as-Bear-McCreary music was fucking amazing in that it only played along with the "what's around the corner" vibe.
In season 6 though, a good majority of the island had been shown-- but like an ocean, there's probably a lot to the island in spite of that. So sure, there's always room for exploration and the such but I think it's nice that they didn't cover every single area and show us every single detail. To counter this, in a way, I felt that season 6 went back to the mystery vibe of season 1, in that we didn't know what this flash-sideways universe was or how it connected to the core storyline-- so in a big way, to me it felt like sliding back into some comfortable old shoes. There was a new element of mystery that didn't have to do with island exploration, but still completely related to the island itself.