The easy answer to this question would be that the NFL Network and mainstream media such as Bleacher Report are pushing this content during the offseason. That would just be a cop out for someone attempting to answer this question without looking further into it.
The media wouldn't push a product if there wasn't a large demand for it. Just look at the Lingerie Football League (one of my favorites) or the now-defunct XFL. Media didn't push those products because no one really cared about them.
It is all about demand and us NFL fans just cannot get enough of the product. There is no longer an offseason in the traditional sense of the word. Instead, this is a game that we revolve ourselves around on a year-round basis.
The Senior Bowl takes place before the NFL season has even ended, prospects declare for the draft extremely early, the NFL scouting combine is a week-long event, collegiate pro days are spread across an entire month and now the draft itself is a three-day event. This doesn't even take into account free agency, which will start in about three weeks.
The NFL has become more than a sport. It is embedded within the American culture, transcending the entertainment sector of our society. For many, it is a major passion; for others (including myself), it has become a quasi-profession.
The combine is no different. It might not be the most entertaining event the NFL could offer, but it is football nonetheless. Fans, scouts, teams, writers, players and executives all take a personal interest in the outcome of the combine because it represents the future of a league we love so much.
In 1982, the National Invitational Camp was first held in Tampa. That year, players like Marcus Allen competed in front of a dwindled down combination of team scouts and coaches. It was nowhere near the level that we see today. Instead, it was rather small in scale.
Fast-forward 20 years and this event is now televised for dozens of hours, written about all over the Internet and attended by every coach from every team around the league. It has become quite the event as fans have started to view it in droves.
It makes perfect sense. The idea of football being a September-to-January sport is over. This idea has been replaced because of the understanding that fans just cannot get enough of the game. In reality, we would watch anything that had the "NFL" ingrained within it if we had an opportunity.
So, yes the combine has become a production but we wouldn't have it any less. Would we?