Why the rule change for onside kicks this year?

I just heard that they changed the rules this year to where the kicking team must have at least 4 players on each side of the kicker on an onside kick where as they used to be able to load the side for effectiveness.

Why the change? Injuries?

Wikipedia claims this article has a cite, but I’m too sick to find it right now.

Injuries. They’re also now in line with the college rule.