The reason for the large packaging is to provide more separation between the individual primers. That way, there is less chance of sympathetic detonation if one goes off for any reason. Federal is also using a different priming compound that is more sensitive, so they've erred on the side of caution in their packaging.
Many years ago, they had a detonation in their plant when an employee shook a container of primers and it went off. The employee was badly injured, so Federal isn't going to take any chances.
Two years ago I showed the Federal reps at the SHOT Show some primers in the old wooden trays they used to package them in. You would have thought I showed them a poisonous spider, as they all backed away and said, "please don't shake that box", which I wasn't about to do anyway. They're pretty gunshy about their primers going off unintentionally.....
Hope this helps.
Fred