you answered your own question. people did pay 60 bucks for it.
also i dont know as i havent opened my copy i just got yet but i also heard it was too much like COD overall. so why play it over COD???
admittely people are hypocrits for hating a game for being too much like COD and only have a 4 hour campaign a complaint i never heard levied against COD.
That complaint was thrown at COD4, which I think was the first super-short campaign. People complained about WAW because, well, I thought it sucked except for the introduction of the zombies. By the time MW2 came around the campaign was expected and there were other multi-player focused issues for people to complain about, lol. And then Black Ops felt like a bit of a longer campaign again.
Homefront is worth $5/$10 for sure. The shooter mechanics are solid enough that if you have nothing else to play, you can play that for a few hours. I got my copy for $5 but was more than happy to trade it into Best Buy for $3.50 or so a couple weeks ago. I didn't even finish the campaign, I got bored with how mundane it all felt. Plus the story just didn't pull me in.