This is a cute post from BuzzFeed mocking people who are frustrated that Lost didn't answer many of its questions. It has a point, of sorts - not all mysteries are worth solving, nor are all answers satisfying - but I think that it's worthwhile to separate out the legitimately frustrating questions from those that either don't require a solution or would simply be better off without one.
So here they are - split into 3 larger groups and 6 smaller categories, 2 categories of which are within each group:
GROUP ONE: Questions that don't need to be answered, and may not have answers anyway
1) Questions that shouldn't be answered because we might as well ask why bad things happen to good people:
* Where did The Island come from? What is The Light? Who created it?
* Where did the Island Guardian powers - like hiding the island or granting Richard immortality - come from? And why, if these powers are so wide-ranging, are they also limited - why couldn't Jacob raise the dead? And, for that matter, why and how was Man in Black able to resurrect Sayid when Jacob couldn't?
* Why is Desmond special?
* Why does the Island heal some things - like Rose's cancer and Locke's spine - and not others - like Ben's cancer?
* How does the donkey wheel work to move the island?
* Why do the sonic fences work against Smokey? How was the ash able to keep him at bay?
2) Questions that shouldn't be answered because it really doesn't matter, does it?:
* Did the bomb go off?
* Was it really Desmond's delay in entering the numbers that caused the plane to crash?
* Was the sideways-universe created by The Incident or the bomb?
* What's the origin of the Ben/Charles feud?
* Was Sayid really turned evil, or, as Hurley said, did he simply become what people expected of him?
* Did the psychic know that Claire had to get on the plane? How?
GROUP TWO: Questions that could use answers, and might have answers, but don't require them
3) Questions that don't need to be answered because the answer seems to already be implied:
* Why can't babies be born on the island, and why was there no such problem in the 70s?
* Was Christian always Christian? Was Smokey sometimes impersonating him? Was he always impersonating him?
* Why wasn't Sun transported back in time?
* Why did Juliet's husband die after she wished it?
* What's the deal with the four-toed, Egyptian statue?
* Was the Dharma Initiative a force of good or bad?
4) Questions that probably don't have a good answer, but whose answers probably aren't important, would be contradictory or needlessly confusing, or simply wouldn't be very illuminating:
* Who was shooting at Sawyer and company's boat when they were being chased across the water during all the time-flashes?
* How was Juliet's sister's cancer cured if Ben's cancer couldn't be?
* Was there really a box that granted wishes? And what is it, really?
* What is the Temple, where do its occupants sit in the Others' hierarchy, and what sort of magical powers does Dogen have that could repel Smokey?
* Why does Sayid, who killed dozens of people as a torturer and then as Ben's lackey, get to go into the Light when Michael, who killed two people - one out of desperation and one accidentally, and only to save his son - but also seemingly redeemed himself, get stuck on the Island?
GROUP THREE: Questions that should be answered (even if they can't be answered)
5) Questions that can't possibly have a good answer, and are probably just evidence of bad planning/writing:
* Why would Chang - or whoever else built The Swan - include Egyptian hieroglyphics in the timer, which are displayed only after it reaches zero?
* If Smokey can only appear as dead people, how did he appear to Locke and Shannon as Walt?
* Why was Richard surprised that Ben could see him when they first met? And why was Harper, who was bringing orders from Ben, able to sneak up on Juliet and disappear just as quickly? Were we meant to understand that the Others could become invisible or travel magically?
* Who was asking Locke to 'help me' in the cabin? And why wasn't he asking Ben, who admitted that no one - Jacob, or someone trying to pass himself off as Jacob - ever spoke to him?
6) Questions that have been dangling for so long or were made to seem so important that we deserved an answer, dammit!:
* Why did small animals die when Walt got angry, and what was so wrong with him that even The Others wanted to get rid of him?
* And relatedly - why are the kids so important? Why do we want to kidnap Walt and Aaron? Why did we kidnap those other children? (It can't just be that they can't procreate on the island, right? And it's not like they knew about Candidates at that point...)
* What's the deal with Eloise and her seeming omniscience, in both the living-day present and in the afterlife?
* What's the deal with the Hanso family, who were the financiers behind both The Black Rock and Dharma and were featured prominently in the Lost Alternate Reality Game?
* What's the Man in Black's name? And if he doesn't have one, why? (Because deliberately not mentioning it seemed significant, at first, and just annoying, later.)
* Do The Numbers refer to the Valenzetti Equation or the final six Candidates? Or both? And how are they related? Is it mere coincidence (?!) or fate that the final six Candidates are assigned the same numbers that appear in the Valenzetti Equation? And if it's the latter, how does that compromise Jacob's whole 'i want you to have a choice' speech, or diminish the centuries-long process of finding a suitable replacement and watching most of the Candidates die in the process?
There are probably other categories that we could invent, and some people can probably take issue with where I've slotted particular questions. Let me know.