Well, I've kinda wondered the same thing. But the difference with mine, instead of, where are the games, I'm asking, where's the genre. Used to be a dungeon crawling, puzzle solving, jump here, fight the boss, next little level, level up, buy new armor, you know made basically what I thought to be the stereo-typical adventure game. A more linear RPG, but these days, it's seems the adventure genre has melted into the RPG genre more then ever. You could argue in some Zelda games whether it is adventure or RPG. And now, what we have is an adventure game every few months that gets classified as other, like Final Fantasy, I think it's adventure not RPG, and yet, when you search it's under RPG, same with Zelda. And Tomb Raider is now a more i dunno, it's just not quite the adventure it used to be, now it's more fighting in some areas, and then all puzzle in other.
So far though, I've looked into some reviews and played a few, that although may be catagorized differently seem to me to be adventure...Prince of Persia (possibly best available in terms of adventure, story, upgrading, etc, the all around adventure game), Beyond Good and Evil, Lord of the Rings ( i feel some adventure there, less RPG), Whiplash (xbox, not sure if has come out, or if it ever will.), Kameo: Elements of power, (same as last game.), The Kore Gang (again all three of these xbox i think, and unsure if released.), Sudeki, Legacy of Kain, Voodoo Vince (more platformer, unsure of release?), CastleVania, Ratchet and Clank, Ape Escape and lastly Ninja Gaiden (although, mostly fighting, it has an adventure feel to it.
Like I said tho, some of these games I've never played, all I've read reviews. To say they are all adventures, probably not, they all have hints of action, or more jumping, or shooting, but from what I take to be adventure, I'd say these come out on top of what's available. But you just gotta check to see what ur game console/system has each game catagorized under. But I would definetly look under RPG, cuz that is where most adventures are heading, simply because an RPG to me, is a more open ended adventure.