Imo, games were NOT made for the gameplay...
Maybe they were, back in the days where I was too young to play computer, but the demand for proper games has made old games like CSS useless crap.
You say that CSS is the foundation of all games? Well, I don't think so. Maybe CoD is basically a CSS ripoff, but BF3 is definitely not. BF3 has tactics, many gamemodes, vehicles, and proper graphics. Therefore, IMO, BF3 is the REAL foundation of FPS games. Even though all FPS games DO include a certain CSS element, its still limited how much you take from that old game.
Man, you are giving BF3 too much credit.
"The REAL foundation of FPS"?, If anything, it should be Doom. The first Really-Well-Known FPS. It's LAN games were amazing for that time, it was the perfect timewaster.
Also, the Tribes series. It had multiple gamemodes, and vehicles, even different classes, all of this in 1998, years before the first BF
So, BF3 is not the real foundation, it is founded on - Well... - the REAL foundation that dates back to 1998 or even before of that.