I kind of look at this record the way I look at different eras in baseball (ignoring the steroid issue) . . . its a different league, with different rules, that Unitas would not recognize. When Unitas, arguable the greatest of all time, was setting this record, defensive backs could hit receivers at any time while they were going down the field, making timing patterns virtually impossible. Defensive linemen were hitting quarterbacks in the head, below the knees, and anywhere else they could, as hard as they could. A receiver coming across the middle of the field took his life in his hands. In today's watered down version of football, with the dramatic rule changes concerning "defenseless receivers", hitting quaterbacks below the knees and above the shoulders, and the 5 yard chuck rule, the fact that it took this long to break the record is a testament to Unitas' greatness.
Think about the list of all-time great quarterbacks that could not break this record, even as the rules were changed more and more to favor passing: Joe Montana, Dan Marino, Steve Young, Troy Aikman, Brett Favre, Tom Brady, Peyton Manning, Aaron Rogers. It took Drew Brees, playing in a dome (another dramatic change in the modern game, weather controlled domes), to finally eclipse Unitas. Well, as far as I'm concerned (and this is taking nothing away from Brees, who is a fantastic QB) there are two records: Unitas still holds the record under the real rules of football is it was intended to be played, Brees holds the record under the "modern" rules of football.