I think you could argue that we're neglecting the other end of the FPS genre too- NO ONE LIVES FOREVER is a great FPS game that isn't just about killing everything on the screen, but it's also unlike most of what's being made now, because it's quirky and funky and genuinely plays around with spy genre mechanics.
I think the issue is, when you start getting into these huge-budgeted core games based on established properties and advertised everywhere and so on, it becomes like a blockbuster movie- the people behind it need to make their money back, so there's a tendency to water down the product and make it look like everything else. "Um, we've got vehicle sections, because everyone wants those, and a really deep dark story with betrayals and twists that set up the next game, and it's wonderfully gritty with excellent bump mapping and the protagonist is a grim, tortured antihero..." etc.
That, I think, is the big problem the video game industry faces- it's gotten so big that it has to appeal to as many people as possible, and so all the technology that's available gets put towards the same ideas and same images. It's like the early sound era, where the technology temporarily set things back because cameras were less mobile and actors all had to stand near the microphones and movies became like stage plays.
