You don't need answers for everything - but they could've made an attempt to explain away some of the dozens of plotholes/inconsistencies, etc. they've compiled in the past couple of years.
Ultimately, now that I've come to accept that the show is simply not of the quality I once thought it was, I found the finale extremely enjoyable. The characters - thanks to the actors - are extremely engrossing.
I do have to wonder how much better this saga would have turned out had it not been in the hands of guys who were previously best known for Nash Bridges. Much like many to come before them (George Lucas, for instance), they are amazing at the big picture, but butcher the craft of writing. Frankly, even the other writers on the LOST staff are much better - and I would've loved to seen Horowitz/Kitsis pen the finale.