The problem with the LOST ending was, it wasn't planned. They wrote themselves into a corner.
I'm good with the ending, too. I'm also good with people roasting them for it. And I'm also good with situations like in FROM where Harold Perrineau said he wouldn't work with them (same people) if they didn't have the ending pre-planned in advance. They even poke fun at the LOST ending in one of the early episodes, implying it won't go that way.
Dexter technically hasn't ended, unless you mean the series Dexter.
There have been two spinoffs, and the second one hasn't ended yet. So for the people who say Dexter should have died/been exposed/caught/shamed at the end... well... it hasn't ended yet.
Also, the books are wilder. In the last one I read, the little boy and girl of Rita's were getting into killing. The little girl says "I don't kill because I'm a girl, so I'm just the lookout for my brother." The brother kills animals, the girl watches out, distracts anyone who might come around, basically runs interference for him. IIRC they're twins and maybe the book tried the whole "psychic twin connection" stuff? It's been a while. The book just gave creepier vibes than the previous ones and I quit there.
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Also let's not forget Cyber Doakes! That was wild.