Re: Why does COD always get more sales over other better FPS games?
The 'it takes no skill' argument is bogus, but it still is a game you can pick up and play. You might suck for a little while if you've never played CoD before, but the learning curve isn't as big as other games with more intricate controls and storylines.
Also as ballup said, YouTube in particular has helped CoD go mainstream with commentaries over the past few years, and the amount of people who make a living (and a damn good one at that) producing YouTube gameplay commentaries is constantly growing. Nowadays it's a lot more about the commentator personalities, and people enjoy more variety, but when it first got big, it was CoD vids or nothing if you wanted to get well known in the YouTube commentating scene.
While it probably doesn't appeal to a lot of people here, and I rarely watch it myself, but competitive CoD as an e-sport is also extremely popular, and audience figures constantly grow. Certain 'teams' have gone pro, and even live together so they can play CoD for god knows how many hours a day. Not on a level of LoL or Dota, but it's still big. Doesn't do it for me personally, but to some kids, these pro-gamers are their heroes.