Well, maybe you iz, an' maybe you isn't, but even if you is, it don't mean you're wrong!
Again, the "They're on an alien space station" theory was proposed in season one, as that comic book of Hugo's that Walt was reading took place on one, as well...
With this show, who knows?
Here's another thought, or a couple:
The strange EM effects of the island cause compasses to vear off, near the island. We know that the one Locke gave Sayid, last season, surely did. This could help explain why various ships and planes wind up here...
Also, perhaps the code hasn't been entered, on time, several times, over the years... An EMP (Electro-magnetic pulse) would wipe out all the electronics (unless heavily shielded, depending upon the power of the pulse), and would certainly explain modern ships and planes (with electronic instrumentation) going down, or wrecking. A simple trawler (which is what the boat that captured Walt looked like), and a shielded broadcast station might be able to survive the EMP (the trawler's engines certainly would).
Maybe the "disease" that Danielle Rouseau & Desmond are so worried about is radiation poisoning from a bomb, on countdown?