Well what probably helped Bad Company 2 is coming off of Modern Warfare 2. Although, the developers are trying to distance themselves from the title, more than likely there are a lot of gamers looking to move on to the next thing and Bad Company 2 offered that... more so than MAG could have. That probably helped turned BC2 into a much bigger game than usual.
Obviously Final Fantasy is a big western title, but it's not the same big title that we see in Japan. In Japan it is top 5 biggest franchises, but in the West it doesn't even make the top 10 over the last 10 years. I think people get confused because FF is a huge core franchise, but not anything that sells vastly to the mainstream... something BC2 does do for being a mainstream genre.
