Ehh... only sorta agree with you there, Urist.
Definitely, games are targeting the "casual hardcore" crowd, which want to be able to just feel awesome without too much work. The casual crowd, who want much less work and don't like the tropes used in video games, is left out (save for the Wii, but that's a can of worms that doesn't need opening right now,) and the hardcore crowd, who want to see something new and exciting and would like a little work in their game, generally gets left out.
And yes, games are very genre-oriented. A shooter will always have you as a one man army badass, capable of getting shot multiple times in the chest and being fine after some bandages and thirty seconds; an RPG will always have you as a spunky young hero who's about to uncover some sort of evil secrets and maybe some romance too; etc.
What you're missing is that these games play well. They take genre elements and, though they don't revolutionize them, they definitely turn them into a playable game--a worthwhile game. Sure, GoW and Halo are the same thing with different guns and voice-actors, but they both use a winning formula, use it well, and mix it up enough that the player feels like s/he's accomplishing something. It's not a great strategy, but it's a good strategy.
These are the games that hype works on. Look at the hype machine for Fable 2--They tried to get some word out, but the game wasn't really that good, it messed with some pretty key mechanics in unfathomable ways, and more. The word didn't get out because noone knew what was happening, and the developers, instead of releasing more hype-worthy footage, complained that noone understood them.
Versus GoW 1, which had the standard 3rd person shooter elements plus some better cover controls. Showing the gameplay with the cover was immediately intuitive, immediately interesting, and got everyone into a froth about how this was the "future" of gaming--more realistic combat and cover.
And, though they're both genre, GoW 1 is much higher quality (in terms of gameplay experience) than Fable 2.
So, to sum up: hype is created when a game is "good enough" and marketed well. Sure, it might not be very good by your standards, but it doesn't have to be--just "good enough."