the rough country kit is set up to remove rivets and redrill the holes to bolt the brackets on

 

That is for placement, so they are installed correctly. You still have to weld them.

 

the instructions gave it as an option, but gave torque values if you didnt

 

Well, it's entirely up to you if you feel safe with it not welded. If you look around at other kits it's not an option. That's a lot of extra stress on the crossmember, which makes it crack. Their brackets may be designed differently than the other kits though.