First off, anyone who calls you a hater is ridiculous - your criticisms are well-stated, cogent, and rational (as usual).
My one issue with this point, and some of your other analysis, is that I think there's a difference between using mystery and being a mystery. Earlier, you judged this balance by looking at commercial act-breaks, arguing that ending an act (or an episode, or a season) on pure mystery indicates that the show is predicating itself on mystery.
In some instances, I think you're spot on: the final scene of the first season is by far the worst example of this, presenting the hatch without any hint at what they were actually about to do with it. However, in the end, the hatch ended up creating some of the series' most compelling character actions/reactions, and the way the pure mystery became the stunning opening to the second season indicates that there are ways in which that mystery can pay off in terms of the characters. It didn't remain a mystery forever, which is why using mystery is not the same as being a mystery: if all of the character has suddenly banded together in order to solve the mystery of the four-toed statue, then I'd be on the same page, but the fact that it remained in the periphery is the show simply building suspense like any other show on television.
You're right that the show never found the perfect balance, but I think this is something they accepted as part of the complex relationship between author and audience. The interesting thing about Lost is that as the mysteries became more important to a subsection of fans as the series came to its conclusion, the mysteries became less important within the show itself. If you look at the first season, the characters were defined by their mysteries: they worried about the black smoke, they fought against the Others, and they worked to try to escape this chaos. By the time the fifth season came along, meanwhile, the groups were divided: Sawyer and Juliet were living happily in the 70s, perfectly willing to ignore the island's "mysteries" and live out their lives. Suddenly, some of the characters weren't as interested in mysteries as others, an extension of the Faith/Science debate that took place in early seasons. And those who <i>were</i> trying to solve mysteries like Jack were doing so to find their own purpose, not the purpose of the island, just as Kate returned to find Claire as opposed to figuring out why the Polar Bear* was there.
*Just on that note: my single favourite "answer" in the entire series was the polar bear that Charlotte finds in Tunisia coming full circle when Ben turned the wheel. The show doesn't show the polar bears being used as a way to "move" the island (able to live in the cold conditions beneath the Orchid), but it's all there for us to figure out.
The Freighter folks are a fine example of this: they all came to the island to solve its mysteries, perfectly suited to figure things out, and yet all of them get caught up in the story and never really get to solve the mysteries they came to solve. Perhaps there is your turning point: the show creates characters who could answer our questions and all they do is start asking questions of their own as they get caught up in the drama of it all. At around that point in the series, after "Through the Looking Glass," the show made a pretty definitive statement in its storylines that mysteries no longer governed character action the way they did earlier in the series - of course, at the same time, the unsolved mysteries were festering for those viewers who simply weren't on the same page.
And as you say, the show never stopped "using" mystery in order to get from episode to episode, or to build suspense in the sixth season in regards to the true function of the flash sideways, so it's not that these people are crazy. Rather, it's just that they kept seeing the forest for the giant monster moving through it rather than the trees, something that I think Lindelof and Cuse were well-aware of and chose to ignore. I respect their right to do so, and while I think it created a more flawed series as a whole I don't think it tarnishes their purpose nor their accomplishments in pulling off something this ambitious on network television.
Ask and you shall receive: I took part in two podcasts on Thursday that fit your bill to some degree.
The first seems perfect: TV critics and scholars discussing the finale and the series' legacy as a whole. No one really disliked the finale, but there's some discussion of its flaws, and some great observations by a whole bunch of intelligent people.
TV on the Internet, Episode 37: Lost [Media Elites]
The second is a bit more confrontational, which would perhaps be better for those who didn't like the finale and wanted that viewpoint expressed and analyzed in detail. There's representation from both sides (I guess I'd be on the Lost Defence Force, in this instance), and I thought we got to flesh out some of the more base concerns with the finale in a productive fashion.
The /Filmcast Bonus Ep. Lost Series Finale and Wrap-up [/Film]