[Jeritron]

There are certain mysteries that will be left, and I think should be left, so that people will continue to talk about it. Mystery is one of the biggest aspects of the show, and although the big questions need closure, I have no problem with some of it remaining.
So far most of the burning questions have been given answers. I think there'll still be some more big answers to come.

I always felt like the sickness was either a mindfuck from Dharma, or their misunderstanding of MIB's ability to claim, as we saw with Roussea's team and Sayid.
Death during birth is another mystery I'm content with being left alone. I always saw that as the island's will. The Island/Jacob or whatever brings certain people to the island, and does away with certain people. It has no need for new life being created on it's watch.

I haven't thought about the Dharma supply drop in a while. That's definitely an unsolved mystery, but I always thought it was a result of the time pocket on the planet. Remember how it took the helicopter back in time by an hour or so before it reached the island? Or how the probe Faraday sent out arrived 15 minutes later or whatever?
Same with the boat captain that had his throat slit, and washed up on shore before it actually happened on the boat.
These things were all signs to me that the Dharma supply drop was probably made at an earlier point in history, when Dharma was still alive and kicking, but didn't reach the island until 2004.

Then there are loosely solved mysteries. The numbers have had various meanings throughout the shows, and until now the last meaning was The Candidates. It's just a number pattern that continually appears in key situations, and either has spiritual meaning or coincidental meaning. Leaving it mysterious and open to discussion really seems the better option.