I don't know if the 'island is a cork' is much of an answer, I mean an island is just an island, a body of water in the middle of the ocean. You need further explanation about the island itself to consider that a real answer I think.
Why couldn't he just hop on all the helicopters or subs that have come and gone? It's sort of like saying, hey Scranton Pennsylvania is a prison for evil, and just leaving it at that. Um, HOW is that town a prison, it's just a town.
What's with the donkey wheel? Who put that there? How does it work?
Who are Jacob and the Man in Black? Are they just supernatural stand-ins for god and the devil? I could maybe buy that as an answer that needs no further elaboration. But then who's the kid Smokey saw?
What DOES need a little elaboration is the mechanical "science-y" nature of Smokey. The way it scans people's brains, the electronic churning cranking sounds. I suspect this won't be answered because they plotted out the series during the S1-2 haitus, after introducing Smokey, so I imagine in S2 they were retrofitting their new idea with what they put onscreen in Exodus.
(ironically, the answer that nobody actually wants, explains it all nicely, they're aliens, the island is a spaceship, it has its own power source and can move between space and time, etc etc. I'm not saying I want to see this I'm over the whole aliens thing, but i just think its funny the most reviled theory explains everything)
All that stuff with some of the O6 being white-flashed back to 77, why were they flashed? What was the purpose? I'm uncomfortable with the idea that the island just picked those specific people and flashed them back, without there being a logical reason. That was all very "hand-wavey" by the writers, and the sort of thing that gives genre writers a bad name. There needs to be a concrete reason given why that all happened.