It's to fill the gap between the conference championships and the SB. Better ratings ($$$) than playing this in FEB. In JAN, people are still pumped up for football, with the SB just around the corner.
Agree with the opinion though that they should just get rid of this game and make the pro bowl just an award for the players. Keep the skill competitions and the like, but just axe the game. Maybe make something with the players and the fans more interactive to still give people a reason to fly out to Hawaii. But will probably never happen since the NFL won't want to lose the revenue from the game itself.