I think there's a distinction to be made here - in my opinion the final episode was about the characters, that doesn't mean the whole final season was. They tried to deal with some of the mythology there (albeit in a way that still threw up questions), it's just that by then they'd left Dharma/The Others/any SF elements behind to focus on Jacob and his brother. And by just making the last episode a character piece it made the ending more moving for me.

And I have to disagree with some of what's being said, yes of course the mysteries were part of what kept me watching, but so were the characters. If the entire show had been populated by Shannon-clones I wouldn't have made it past episode one. Sawyer and Hurley alone made the show 50% more watchable.