i won't attempt to disagree with your list because, frankly, i can't - there are some real corkers in that list. i even agree about the shoddiness of of silent hill 4 - but i disagree with your reasoning of why you like those games
the first rule of statistics is "correlation does not imply causation". you like good games adult games - but that does not mean adultness causes goodness. there are a plethora of games with adult themes which are, frankly, childish in execution and tone (e.g. the punisher, or manhunt, or whatever. i could list a few hundred if it makes you feel better)
the games you list are great games because they have deep, moving stories, immaculate presentation. the characters provoke emotion, you care about their stories, and the atmosphere of the game draws you in enough to immerse yourself in the experience. silent hill 4 falls flat not because you're bored of the concept, but because it's got characters more wooden then keanu reeves, and four cliche'd levels (which you have to play through twice) full of unfair monsters and illogical settings
and just as you can find some real dross "for kids" (e.g. any THQ movie-licensed game), you can equally find some games with all the same tickboxes as your first list - say, Psychonauts, Okami, Beyond Good & Evil.
it's not gore that makes a game appeal to adults, it's experiences more engrossing than "
lol i r teh violent killar", which is equally shallow whether the target is throwing someone in a wood chipper versus jumping on a cliche'd platform monster's head
i enjoy being told a story. pixar tell good stories as much as tarantino.