Oh, merciful amnesia! Been a LONG time since I did those....
Yeah, some value; less for the knuckle-toughening, but more to focus on the big knuckles so it becomes second nature to strike with them. Ask any cop, he'll tell you how to find someone who was in a stupid fist fight. "Look for the guy with the busted hand" from punching with the weaker knuckles.
My hands are too valuable to me to go whole-hog on breaking techniques, but a little toughening up of the big knuckles is reasonable.