The Lost writers clearly had no idea how to wrap up the mythology despite promises otherwise all along and instead chugged it and tried to pass off this whole notion that the viewers shouldn't care about the mythology(even though what made LOST so engrossing were the mythology elements afterall go to a thread or a water cooler and everyone was talking mysteries no the character stuff) because it was all about the characters--but really if you look back at the final season most of the characters were plot devices or had storylines no one was interested in like Kate.
First off, I'll disagree that that "everyone was talking mysteries not the character stuff." Personally, Lost was
always about the characters -- it invested heavily in character development in its first season and much of it second. That's why the mysteries were so compelling -- viewers (well, me at the very least

)
cared about the characters.
I will agree, though, that as the series continued, the focus shifted very heavily toward plot -- toward the "big twist of the week." And, overall, that hurt the show. But the finale's focus on character was entirely consistent with its beginning. So to say that it was a complete surprise would be to ignore the series as a whole.
And by the way, for BSG, it was quite frequent that "characters were plot devices." There were shifting allegiances, behaviors, motivations of the characters to suit the BSG mythos. The Final Five are a perfect example of that -- namely their characters suddenly changed to meet the quote of five additional Cylons.
LOST's finale was also hurt judging it on its own apart from its place in the series by a weak fight between Smokey and Jack, a plodding pace, the afterlife build-up was tedious even though the final payoff was poignant. And there is no comparing the character scenes and emotional payoff-BSG was superior in every way with Roslin's death, Starbuck's goodbye, the death of Anders, Six and Baltar, the beautifully done melancholy existing right alongside hope. LOST's finale really didn't have those things.
I agree both sucked at the plot/mythology in the finale.
See ... your comments like "the after-life buildup was tedious" and "no comparing the character scenes and emotional payoff" are exactly what I mean by personal preference. BSG's finale worked for you. That's cool. Personally, Lost's finale worked for me -- it was visceral -- while I found BSG to be almost bereft of emotion (particularly considering how the characters ended up). But that's just my preference. The fact remains,
both finales were heavily character-centric at the expense of plot -- admittedly so by both Moore and Lindelof.
Indeed. That was my point. If BSG had just abandoned plotlines (like finding Earth, battling the Cavill Cylons, and the cancer of Roslin) and just had everyone meet up in the afterlife reflecting on "hey, at least we had some good times together, right?"... THEN there might be a comparison. But the finales are drastically different. They are flawed in different ways, IMO.
I agree that the finales are flawed in different ways in terms of specifics (i.e. in BSG just about everyone split up, in Lost they all came together again), but both finales were explicit in their character-driven focus. And, in that context, they both work. Like I said, there's personal preference involved in terms of which works better. But let's be honest and at least admit that BSG was no more concerned about plot than Lost.
By the way, I think "pulling a Lost" is more relevant to finale letdowns than "pulling a BSG" because Lost had a much wider audience.