Quite a few people are getting a bit defensive about this.
You have a point but not entirely....IMHO, he's marketable for more reasons than merely Federer.
However, you can't deny that a guy like Roddick gets more attention because he's born in the US.
Nothing against the US and people don't choose where they are born but if players like Moya, Ferrero, Gaston Gaudio or Thomas Johansson (these guys are attractive + slam winners) were born in the US, they would receive more attention in the media. It's as simple as that.
Suppose Roddick was born in Spain and Moya in the US...what effect would that have on their impact in the media?